Surgical robot platform

ABSTRACT

A medical robot system, including a robot coupled to an effectuator element with the robot configured for controlled movement and positioning. The system may include a transmitter configured to emit one or more signals, and the transmitter is coupled to an instrument coupled to the effectuator element. The system may further include a motor assembly coupled to the robot and a plurality of receivers configured to receive the one or more signals emitted by the transmitter. A control unit is coupled to the motor assembly and the plurality of receivers, and the control unit is configured to supply one or more instruction signals to the motor assembly. The instruction signals can be configured to cause the motor assembly to selectively move the effectuator element.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/466,937 filed on Mar. 23, 2017 (published as U.S. Pat. Pub. No.2017/0239007), which is a continuation of U.S. patent application Ser.No. 13/924,505 filed on Jun. 21, 2013, now U.S. Pat. No. 9,782,229,which is incorporated herein by reference in its entirety for allpurposes. Application Ser. No. 13/924,505 claims priority to U.S.Provisional Pat. App. No. 61/662,702 filed Jun. 21, 2012 and U.S.Provisional Pat. App. No. 61/800,527 filed Mar. 15, 2013, which areincorporated herein by reference in their entireties for all purposes.

BACKGROUND

Various medical procedures require the precise localization of athree-dimensional position of a surgical instrument within the body inorder to effect optimized treatment. Limited robotic assistance forsurgical procedures is currently available. One of the characteristicsof many of the current robots used in surgical applications which makethem error prone is that they use an articular arm based on a series ofrotational joints. The use of an articular system may createdifficulties in arriving at an accurately targeted location because thelevel of any error is increased over each joint in the articular system.

SUMMARY

Some embodiments of the invention provide a surgical robot (andoptionally an imaging system) that utilizes a Cartesian positioningsystem that allows movement of a surgical instrument to be individuallycontrolled in an x-axis, y-axis and z-axis. In some embodiments, thesurgical robot can include a base, a robot arm coupled to and configuredfor articulation relative to the base, as well as an end-effectuatorcoupled to a distal end of the robot arm. The effectuator element caninclude the surgical instrument or can be configured for operativecoupling to the surgical instrument. Some embodiments of the inventionallow the roll, pitch and yaw rotation of the end-effectuator and/orsurgical instrument to be controlled without creating movement along thex-axis, y-axis, or z-axis.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial perspective view of a room in which a medicalprocedure is taking place by using a surgical robot.

FIGS. 2A-2B display a surgical robot in accordance with one embodimentof the invention.

FIG. 3 illustrates a surgical robot system having a surveillance markerin accordance with one or more embodiments described herein.

FIG. 4 illustrates an example of a methodology for tracking a visualpoint on a rigid body using an array of three attached markers inaccordance with one embodiment of the invention.

FIG. 5 illustrates a procedure for monitoring the location of a point ofinterest relative to three markers based on images received form themethodology illustrated in FIG. 4.

FIGS. 6A-6F illustrates examples of tracking methodology based on anarray of three attached markers in accordance with one embodiment of theinvention.

FIG. 7 illustrates an example of a two dimensional representation forrotation about the Y-axis in accordance with one embodiment of theinvention.

FIG. 8A-8C illustrate alternative representations of a two dimensionalrepresentation for rotation about an X-axis in accordance with oneembodiment of the invention.

FIG. 9 provides a depiction of a noise within a frame of data.

FIG. 10 illustrates the depiction of a noise within a frame of data asshown in FIG. 9 with a stored point of interest.

FIG. 11 illustrates a depiction of results of applying a least squaresfitting algorithm for establishing a reference frame and transformingmarkers in accordance with one embodiment of the invention.

FIG. 12 illustrates a depiction of results of applying a least squaresfitting algorithm for establishing a reference frame and transformingmarkers as shown in FIG. 11 including noise.

FIG. 13 illustrates a depiction of error calculation for reference framemarkers in accordance with one embodiment of the invention.

FIG. 14 illustrates a graphical representation of methods of trackingthree dimensional movement of a rigid body.

FIG. 15 shows a perspective view illustrating a bayonet mount used toremovably couple the surgical instrument to the end-effectuator inaccordance with one embodiment of the invention.

FIGS. 16A-16F depict illustrations of targeting fixtures in accordancewith one embodiment of the invention.

FIG. 17A shows an example illustration of one portion of a spine withmarkers in accordance with one embodiment of the invention.

FIGS. 17B-17D show various illustrations of one portion of a spine withtwo independent trackers with markers in accordance with one embodimentof the invention.

FIGS. 17E-17F illustrate a representation of a display of a portion of aspine based on the location of a tracker in accordance with oneembodiment of the invention.

FIGS. 17G-17H represent images of segmented CT scans in accordance withone embodiment of the invention.

FIG. 18 shows an example of a fixture for use with fluoroscopic views inaccordance with one embodiment of the invention.

FIGS. 19A-19B illustrates expected images on anteroposterior and lateralx-rays of the spine with a misaligned fluoroscopy (x-ray) machine inaccordance with one embodiment of the invention.

FIGS. 20A-20B illustrates expected images on anteroposterior and lateralx-rays of the spine with a well aligned fluoroscopy (x-ray) machine inaccordance with one embodiment of the invention.

FIGS. 21A-21B illustrates expected images on anteroposterior and lateralx-rays of the spine with a well aligned fluoroscopy (x-ray) machineincluding overlaid computer-generated graphical images showing theplanned trajectory and the current actual position of the robotend-effectuator in accordance with one embodiment of the invention.

FIGS. 22A-22B illustrates expected images on anteroposterior and lateralx-rays of the spine with a well aligned fluoroscopy (x-ray) machineshowing a feature on the targeting fixture designed to eliminateambiguity about directionality in accordance with one embodiment of theinvention.

FIG. 23 illustrates an axial view of a spine showing how a cartoonishaxial approximation of the spine can be constructed based on lateral andanteroposterior x-rays in accordance with one embodiment of theinvention.

FIGS. 24A-24B illustrates examples of targeting fixtures that facilitatedesired alignment of the targeting fixture relative to the x-ray imageplane in accordance with one embodiment of the invention.

FIGS. 25A-25B illustrates expected images on anteroposterior and lateralx-rays of the spine with a well aligned fluoroscopy (x-ray) machine whenparallax is present in accordance with one embodiment of the invention.

FIG. 26A illustrates two parallel plates with identically positionedradio-opaque markers in accordance with one embodiment of the invention.

FIG. 26B illustrates resulting expected x-ray demonstrating how markeroverlay is affected due to parallax using the two parallel plates asshown in FIG. 26A in accordance with one embodiment of the invention.

FIG. 27 shows a representation of the rendering of a computer screenwith an x-ray image that is affected by parallax overlaid by graphicalmarkers over the radio-opaque markers on two plates that have the samegeometry in accordance with one embodiment of the invention.

FIG. 28 shows a graphical overlay for the x-ray image screen intended tohelp the user physically line up the x-ray machine to get a view inwhich the markers on the two calibration plates shown in FIG. 26A in thecase where parallax complicates the view in accordance with oneembodiment of the invention.

FIG. 29 illustrates a method in accordance with at least one embodimentof the invention.

FIGS. 30A-30C illustrates various embodiments of an end-effectuatorincluding a modified mount with a clamping piece in accordance with atleast one embodiment of the invention.

FIGS. 31-32 illustrate embodiments of clamping piece actuation on aspinous process in accordance with some embodiments of the invention.

FIGS. 33A-33B illustrate a clamping piece modified with a targetingfixture including a temporary marker skirt and with the temporary markerskirt detached, respectively, in accordance with at least one embodimentof the invention.

FIG. 34 shows a modified Mayfield frame 6700 including one possibleconfiguration for active and radio-opaque markers in accordance with oneembodiment of the invention.

FIG. 35 shows end-effectuator 30 that includes nested dilators inaccordance with at least one embodiment of the invention.

FIGS. 36A-36C illustrates various embodiments of an end-effectuatorincluding cylindrical dilator tubes in accordance with at least oneembodiment of the invention.

FIG. 37 illustrates a method in accordance with at least one embodimentof the invention.

FIGS. 38A-38B illustrate a robot end-effectuator coupled with a curvedguide tube and a straight guide tube, respectively, for use with acurved or straight wire or tool in accordance with at least oneembodiment of the invention.

FIG. 39 illustrates a guide tube in accordance with at least oneembodiment of the invention.

FIG. 40 illustrates a steerable and trackable needle in accordance withat least one embodiment of the invention.

FIG. 41 illustrates one embodiment of intersecting and interlocking bonescrews in accordance with at least one embodiment of the invention.

FIG. 42A-42B illustrates configurations of a robot for positioningalongside a bed of a patient that includes a targeting fixture coupledto an end-effectuator using a snap-in post.

FIG. 43 illustrates a surgical robot having a plurality of opticalmarkers mounted for calibration and tracking movement in accordance withone embodiment of the invention.

FIG. 44 illustrates a CT scan and methods in accordance with oneembodiment of the invention.

FIG. 45 illustrates a biopsy tool in accordance with one embodiment ofthe invention.

FIG. 46 illustrates a deep brain stimulation electrode placement methodperformed by the robot system in accordance with one embodiment of theinvention.

FIG. 47 illustrates a partial view of a surgical robot system includinga visual indicator comprising lights projected on the surgical field inaccordance with one embodiment of the invention.

FIG. 48 illustrates a perspective view of a robot system including acamera arm in accordance with one embodiment of the invention.

FIGS. 49A-49B illustrate front-side and rear-side perspective views,respectively, of a robot system including a camera arm in a storedposition in accordance with one embodiment of the invention.

FIG. 50 shows a lateral illustration of a patient lying supine, showingthe normal relative positions of the prostate, rectum, bladder, andpubic bone.

FIGS. 51A-51B show lateral illustrations of a patient lying supine,showing how inflation of a balloon and shifting of a paddle in therectum, respectively, can cause anterior displacement of the prostatetoward the pubic bone, and a controllable amount of compression againstthe pubic bone in accordance with one embodiment of the invention.

FIG. 52 shows a sketch of a targeting fixture and immobilization deviceto be used for tracking the prostate during image-guided surgicalprocedures in accordance with one embodiment of the invention.

FIG. 53 shows an illustration of the device as illustrated in FIG. 52,in place in the rectum with prostate compressed and immobilized andtracking markers visible protruding caudal to the rectum in accordancewith one embodiment of the invention.

FIG. 54 illustrates a demonstration of a fibre Bragg grating (“FBG”)interrogation technology with a flexible fiber optic cable in accordancewith one embodiment of the invention.

FIG. 55 illustrates a tracker attached to the surface of the skin of apatient and rigidly interconnected to a fiber optic probe to allowaccurate tracking of the prostate in accordance with one embodiment ofthe invention.

FIG. 56 illustrates the fiber optic probe as depicted in FIG. 55 withoptically visible and MRI visible markings in accordance with oneembodiment of the invention.

FIGS. 57-60 illustrate various embodiments of a fiber optic probetracking system to allow accurate tracking of the prostate forimage-guided therapy in accordance with one embodiment of the invention.

FIG. 61 illustrates one embodiment of a nerve sensing probe.

DETAILED DESCRIPTION

Referring now to FIGS. 1 and 2A, some embodiments include a surgicalrobot system 1 is disclosed in a room 10 where a medical procedure isoccurring. In some embodiments, the surgical robot system 1 can comprisea surgical robot 15 and one or more positioning sensors 12. In thisaspect, the surgical robot 15 can comprise a display means 29, and ahousing 27. In some embodiments a display can be attached to thesurgical robot 15, whereas in other embodiments, a display means 29 canbe detached from surgical robot 15, either within surgical room 10 or ina remote location. In some embodiments, the housing 27 can comprise arobot arm 23, and an end-effectuator 30 coupled to the robot arm 23controlled by at least one motor. For example, in some embodiments, thesurgical robot system 1 can include a motor assembly 155 comprising atleast one motor. In some embodiments, the end-effectuator 30 cancomprise a surgical instrument 35. In other embodiments, theend-effectuator 30 can be coupled to the surgical instrument 35. As usedherein, the term “end-effectuator” is used interchangeably with theterms “end-effectuator,” “effectuator element,” and “effectuatorelement.” In some embodiments, the end-effectuator 30 can comprise anyknown structure for effecting the movement of the surgical instrument 35in a desired manner.

In some embodiments, prior to performance of an invasive procedure, athree-dimensional (“3D”) image scan can be taken of a desired surgicalarea of the patient 18 and sent to a computer platform in communicationwith surgical robot 15. In some embodiments, a physician can thenprogram a desired point of insertion and trajectory for surgicalinstrument 35 to reach a desired anatomical target within or upon thebody of patient 18. In some embodiments, the desired point of insertionand trajectory can be planned on the 3D image scan, which in someembodiments, can be displayed on display means 29. In some embodiments,a physician can plan the trajectory and desired insertion point (if any)on a computed tomography scan (hereinafter referred to as “CT scan”) ofa patient 18. In some embodiments, the CT scan can be an isocentricC-arm type scan, an O-arm type scan, or intraoperative CT scan as isknown in the art. However, in some embodiments, any known 3D image scancan be used in accordance with the embodiments of the inventiondescribed herein.

In some embodiments, the surgical robot system 1 can comprise a controldevice (for example a computer 100 having a processor and a memorycoupled to the processor). In some embodiments, the processor of thecontrol device 100 can be configured to perform time of flightcalculations as described herein. In one embodiment, the end-effectuator30 can be a tubular element (for example a guide tube 50) that ispositioned at a desired location with respect to, for example, apatient's 18 spine to facilitate the performance of a spinal surgery. Insome embodiments, the guide tube 50 can be aligned with the z axis 70defined by a corresponding robot motor or, for example, can be disposedat a selected angle relative to the z-axis 70. In either case, theprocessor of the control device (i.e. the computer 100) can beconfigured to account for the orientation of the tubular element. Insome embodiments, the memory of the control device (computer 100 forexample) can store software for performing the calculations and/oranalyses required to perform many of the surgical method steps set forthherein.

Another embodiment of the disclosed surgical robot system 1 involves theutilization of a robot 15 that is capable of moving the end-effectuator30 along x-, y-, and z-axes (see 66, 68, 70 in FIG. 2B). In thisembodiment, the x-axis 66 can be orthogonal to the y-axis 68 and z-axis70, the y-axis 68 can be orthogonal to the x-axis 66 and z-axis 70, andthe z-axis 70 can be orthogonal to the x-axis 66 and the y-axis 68. Insome embodiments, the robot 15 can be configured to effect movement ofthe end-effectuator 30 along one axis independently of the other axes.For example, in some embodiments, the robot 15 can cause theend-effectuator 30 to move a given distance along the x-axis 66 withoutcausing any significant movement of the end-effectuator 30 along they-axis 68 or z-axis 70.

In some further embodiments, the end-effectuator 30 can be configuredfor selective rotation about one or more of the x-axis 66, y-axis 68,and z-axis 70 (such that one or more of the Cardanic Euler Angles (e.g.,roll, pitch, and/or yaw) associated with the end-effectuator 30 can beselectively controlled). In some embodiments, during operation, theend-effectuator 30 and/or surgical instrument 35 can be aligned with aselected orientation axis (labeled “Z Tube” in FIG. 2B) that can beselectively varied and monitored by an agent (for example computer 100)that can operate the surgical robot system 1. In some embodiments,selective control of the axial rotation and orientation of theend-effectuator 30 can permit performance of medical procedures withsignificantly improved accuracy compared to conventional robots thatutilize, for example, a six degree of freedom robot arm 23 comprisingonly rotational axes.

In some embodiments, as shown in FIG. 1, the robot arm 23 that can bepositioned above the body of the patient 18, with the end-effectuator 30selectively angled relative to the z-axis toward the body of the patient18. In this aspect, in some embodiments, the robotic surgical system 1can comprise systems for stabilizing the robotic arm 23, theend-effectuator 30, and/or the surgical instrument 35 at theirrespective positions in the event of power failure. In some embodiments,the robotic arm 23, end-effectuator 30, and/or surgical instrument 35can comprise a conventional worm-drive mechanism (not shown) coupled tothe robotic arm 23, configured to effect movement of the robotic armalong the z-axis 70. In some embodiments, the system for stabilizing therobotic arm 23, end-effectuator 30, and/or surgical instrument 35 cancomprise a counterbalance coupled to the robotic arm 23. In anotherembodiment, the means for maintaining the robotic arm 23,end-effectuator 30, and/or surgical instrument 35 can comprise aconventional brake mechanism (not shown) that is coupled to at least aportion of the robotic arm 23, such as, for example, the end-effectuator30, and that is configured for activation in response to a loss of poweror “power off” condition of the surgical robot 15.

Referring to FIG. 1, in some embodiments, the surgical robot system 1can comprise a plurality of positioning sensors 12 configured to receiveRF signals from the at least one conventional RF transmitter (not shown)located within room 10. In some embodiments, the computer (not shown inFIG. 1) is also in communication with surgical robot 15. In someembodiments, the position of surgical instrument 35 can be dynamicallyupdated so that surgical robot 15 is aware of the location of surgicalinstrument 35 at all times during the procedure. Consequently, in someembodiments, the surgical robot 15 can move the surgical instrument 35to the desired position quickly, with minimal damage to patient 18, andwithout any further assistance from a physician (unless the physician sodesires). In some further embodiments, the surgical robot 15 can beconfigured to correct the path of surgical instrument 35 if the surgicalinstrument 35 strays from the selected, preplanned trajectory.

In some embodiments, the surgical robot 15 can be configured to permitstoppage, modification, and/or manual control of the movement of theend-effectuator 30 and/or surgical instrument 35. Thus, in use, in someembodiments, an agent (e.g., a physician or other user) that can operatethe system 1 has the option to stop, modify, or manually control theautonomous movement of end-effectuator 30 and/or surgical instrument 35.Further, in some embodiments, tolerance controls can be preprogrammedinto the surgical robot 15 and/or processor of the computer platform(such that the movement of the end-effectuator 30 and/or surgicalinstrument 35 is adjusted in response to specified conditions beingmet). For example, in some embodiments, if the surgical robot 15 cannotdetect the position of surgical instrument 35 because of a malfunctionin the at least one RF transmitter, then the surgical robot 15 can beconfigured to stop movement of end-effectuator 30 and/or surgicalinstrument 35. In some embodiments, if surgical robot 15 detects aresistance, such as a force resistance or a torque resistance above atolerance level, then the surgical robot 15 can be configured to stopmovement of end-effectuator 30 and/or surgical instrument 35.

In some embodiments, the computer 100 for use in the system can belocated within surgical robot 15, or, alternatively, in another locationwithin surgical room 10 or in a remote location. In some embodiments,the computer 100 can be positioned in operative communication withpositioning sensors 12 and surgical robot 15.

In some further embodiments, the surgical robot 15 can also be used withexisting conventional guidance systems. Thus, alternative conventionalguidance systems beyond those specifically disclosed herein are withinthe scope and spirit of the invention. For instance, a conventionaloptical tracking system for tracking the location of the surgicaldevice, or a commercially available infrared optical tracking system,such as Optotrak® (Optotrak® is a registered trademark of NorthernDigital Inc. Northern Digital, Waterloo, Ontario, Canada), can be usedto track the patient 18 movement and the robot's base 25 location and/orintermediate axis location, and used with the surgical robot system 1.In some embodiments in which the surgical robot system 1 comprises aconventional infrared optical tracking system, the surgical robot system1 can comprise conventional optical markers attached to selectedlocations on the end-effectuator 30 and/or the surgical instrument 35that are configured to emit or reflect light. In some embodiments, thelight emitted from and/or reflected by the markers can be read bycameras (for example with cameras 8200 shown in FIG. 48) and/or opticalsensors and the location of the object can be calculated throughtriangulation methods (such as stereo-photogrammetry).

As described earlier, the end-effectuator 30 can comprise a surgicalinstrument 35, whereas in other embodiments, the end-effectuator 30 canbe coupled to the surgical instrument 35. In some embodiments, arm 23can be connected to the end-effectuator 30, with surgical instrument 35being removably attached to the end-effectuator 30.

In some embodiments, the surgical robot 15 is moveable in a plurality ofaxes (for instance x-axis 66, y-axis 68, and z-axis 70) in order toimprove the ability to accurately and precisely reach a target location.Some embodiments include a robot 15 that moves on a Cartesianpositioning system; that is, movements in different axes can occurrelatively independently of one another instead of at the end of aseries of joints.

FIG. 3 illustrates an example embodiment 3600 of surgical robot system 1that utilizes a surveillance marker 710 in accordance with one or moreaspects of the invention. As illustrated, the example embodiment 3600comprises a 4-marker tracker array 3610 attached to the patient 18 andhaving a surveillance marker, and a 4-marker tracker array 3620 on therobot 15. In some embodiments, during usage, it may possible that atracker array, or tracker (3610 in FIG. 3), on a patient 18inadvertently shifts. For example, a conventional clamp positioned on apatient's 18 spinous process 2310 where the tracker 3610 is attached canbe bumped by the surgeon's arm and move (i.e., bend or translate) to anew position relative to the spinous process 2310. Alternatively, atracker 3610 that is mounted to the skin of the patient 18 can movegradually with the skin, as the skin settles or stretches over time. Inthis instance, the accuracy of the robot 15 movement can be lost becausethe tracker 3610 can reference bony anatomy from a medical image that nolonger is in the same position relative to the tracker as it had beenduring the medical image scan. To overcome such problems, someembodiments of the invention provide a surveillance marker 710 asillustrated in FIG. 3. As shown, in some embodiments, the surveillancemarker 710 can be embodied or can comprise one or more markers 710rigidly affixed to a patient 18 in a location different than thelocation in which a primary tracker array 3610 is affixed; for example,a different spinous process 2310, on the skin, or on a small postdrilled into the ilium. Accordingly, in some embodiments, thesurveillance marker 710 can be located on the same rigid body as theprimary tracker array 3610 but at a different location on the rigidbody.

In one embodiment, in response to placement of the surveillance marker710, execution of a control software application (e.g., robotic guidancesoftware) can permit an agent (e.g., a surgeon, a nurse, adiagnostician) to select “set surveillance marker”. At this time, thevector (3D) distances between the surveillance marker 710, and each ofthe markers 3611, 3612, 3613, and 3614 on the primary tracker array 3610can be acquired and retained in computer 100 memory (such as a memory ofa computing device executing the control software application). In anembodiment in which a 4-marker tracker array 3610 is utilized (FIG. 3),four distances 3611 a, 3612 a, 3613 a, and 3614 a can be acquired andretained, representing the distances between the surveillance marker 710and markers 3611, 3612, 3613, and 3614. In such embodiment, at eachframe of real-time data during a procedure, the surgical robot system 1disclosed herein can calculate updated distances between each of themarkers 3611, 3612, 3613, and 3614 on the primary tracker array 3610 andthe surveillance marker 710. The system 1 can then compare the updateddistances or a metric thereof (for example, the sum of the magnitude ofeach distance) to the available values (for example, values retained inthe computer 100 memory). In some embodiments, in view that thesurveillance marker 710 and tracker array 3610 can be on the same rigidbody, the updated distances and/or the metric thereof (such as theirsum) can remain substantially fixed unless one or more of the trackerarray 3610 or the surveillance marker 710 shifts. In some embodiments,in response to a shift of the tracker array 3610 or the surveillancemarker 710, or both, a notification can be issued to alert an agent of aloss in movement accuracy. In some embodiments, if the surveillancemarker 710 offset exceeds a pre-set amount, operation of the surgicalrobot system 1 can be halted. In some embodiments, in response to a userintentionally shifting the tracker array 3610 or the surveillance marker710 to a new position, execution of the control software application canpermit overwriting a set of one or more stored distances with new valuesfor comparison to subsequent frames.

In some embodiments, as illustrated in FIG. 3, embodiment 3600 ofsurgical robot system 1 utilizes a surveillance marker 710, a 4-markertracker array 3610 attached to the patient 18, and a 4-marker trackerarray 3620 on the robot 15. It should be appreciated that in someembodiments, the 4-marker tracker array 3620 on the robot 15 canexperience an unintentional shift in a manner similar to that for the4-marker array tracker 3610 on the patient 18. Consequently, in certainembodiments, a surveillance marker (not shown) can be attached to adifferent position on the robot 15 arm than the robot's 4-marker trackerarray 3620 to control, at least in part, such unintentional shift. Insome embodiments, a surveillance marker on the robot 15 may providelesser efficiencies than a surveillance marker 710 on the patient 18 inview that the robot 15 arm can be manufactured with negligible orminimal likelihood of the robot's tracker array 3620 or surveillancemarker (not shown) shifting. In addition or in the alternative, otherembodiments can include means for registering whether the tracker 3620has shifted can be contemplated for the robot's tracker array 3620. Forinstance, in some embodiments, the means for registering may not includea surveillance marker, but may comprise the extant robot 15 trackingsystem and one or more of the available conventional encoders. In someembodiments, the system 1 and encoder(s) can compare movement registeredfrom the tracker 3620 to movement registered from counts of encoders(not shown) on each robot 15 axis. For example, in some embodimentswhere the robot's tracker array 3620 is mounted on the housing 27 thatrotates with the roll 62 axis (which can be farther away from the base25 than the z-axis 70, x-axis 66, y-axis 68, and roll 62 axis) thenchanges in z-axis 70, x-axis 66, y-axis 68, and roll 62 axis encodercounts can provide highly predictable changes in the position of therobot's tracker array 3620 in the coordinate systems of the trackingsystem and robot 15. In some embodiments, the predicted movement basedon encoder counts and tracked 3D position of the tracker array 3620after application of known counts can be compared and, if the valuesdiffer substantially (or values are above a predetermined threshold),the agent can be alerted to the existence of that an operational issueor malfunction. The operational issue can originate from one or more ofa malfunction in the registration of counts (i.e., electromechanicalproblem), malfunction in registration of the tracker's markers 3621,3622, 3623, 3624 (for example, outside of tracking system's optimumvolume), or shift in the position of the tracker 3620 on the robot's 15surface during the move.

It should be appreciated that other techniques (for example, methods,systems, and combinations thereof, or the like) can be implemented inorder to respond to operational issues that may prevent tracking of themovement of a robot 15 in the surgical robot system 1. In oneembodiment, marker reconstruction can be implemented for steadiertracking. In some embodiments, marker reconstruction can maintain therobot end-effectuator 30 steady even if an agent partially blocksmarkers during operation of the disclosed surgical robot system 1.

As described herein, in some embodiments, at least some features oftracking movement of the robot's end-effectuator 30 can comprisetracking a virtual point on a rigid body utilizing an array of one ormore markers 720, such tracking comprising one or more sequences oftranslations and rotations. As an illustration, an example methodologyfor tracking a visual point on a rigid body using an array of threeattached markers is described in greater detail herein, such methodologycan be utilized to implement marker reconstruction technique inaccordance with one or more aspects of the invention. FIG. 4, forexample, illustrates an example of a methodology for tracking a visualpoint 4010 on a rigid body using an array of three attached markers4001, 4002, 4003. In some embodiments, the method includes contemplatinga reference data-frame. In some embodiments, the reference data-framecan be associated with a set of reproducible conditions for the relativepositions of the markers 4001, 4002, 4003, but not necessarily definedlocations.

FIG. 5 illustrates a procedure for monitoring the location of a point ofinterest 4010 relative to three markers 4001, 4002, 4003 based on imagesreceived form the methodology illustrated in FIG. 4 in accordance withsome embodiments of the invention. As shown, the method includestranslation and rotating the markers 4001, 4002, 4003 and point ofinterest 4010 with the conditions as shown. In some embodiments, themethod can include saving the x-axis, y-axis, and z-axis coordinates ofthe point of interest 4010 in this reference frame for future use. Insome embodiments, for each subsequent data-frame the method can includethe steps of; 1) transform the markers 4001, 4002, 4003 using theconditions defined for the reference frame (keeping track of therotations and translations), 2) add the point of interest 4010 (whichwas saved after establishing the reference frame) and 3) transform thepoint of interest 4010 back to the current location of the markers 4001,4002, 4003 using inverses of the saved translations and rotations fromstep 1. In some embodiments, upon or after completing step 1 above, theactual proximity of the markers 4001, 4002, 4003 to their originalreference data-frame is dictated by marker noise and rigid bodyrigidity. In some embodiments, the markers will never overlay perfectlywith their counterparts that were stored when establishing the referenceframe. In some embodiments, the disclosed method can permit the markers4001, 4002, 4003 to get as close as possible to their original relativespacing.

FIGS. 6A-6F illustrate examples of tracking methodology based on anarray of three attached markers 4001, 4002, and 4003 in accordance withsome embodiments of the invention. In some embodiments, the goal can bemarker 4001 on the origin, marker 4002 on the positive x-axis, andmarker 4003 in the x-y plan in a positive y direction (shown in FIG.6A). Assuming a starting configuration as shown in FIG. 6B, in someembodiments, the method can include translating the rigid body so thatmarker 4001 is at the origin as shown in FIG. 6C. In some embodiments,the method can then include rotation about the y-axis so that marker4002 is in the x-y plane (i.e., z=0) (see FIG. 6D). In some embodiments,the method can then include rotating the z-axis so that marker 4002 isat y=0, x coordinate positive (as shown in FIG. 6E). Finally, in someembodiments, the method can include rotating about the x-axis so thatmarker 4003 is at z=0, y coordinate positive. In some embodiments, arecord of the translations and rotations can be retained in order toutilize the negative values to transform position(s) back after addingthe point of interest. In some embodiments, when translating the rigidbody so that the marker 4001 moves to the origin, the vector to add toeach marker's position vector is simply the negative 4001 positionvector. In some embodiments, to determine the values of θ to plug intothe rotation matrices in steps 2, 3, and 4, use the arctangent. Forexample, rotate marker 4002 about the y-axis to z=0 where:

${M2} = \begin{bmatrix}4 \\5 \\6\end{bmatrix}$

FIG. 7 illustrates an example of a two dimensional representation forrotation about the y-axis in accordance with some embodiments of theinvention. As shown, FIG. 7 illustrates one embodiment showing atwo-dimensional representation looking down the axis about whichrotation occurs (e.g., y-axis is going into the page). In this example,a position rotation of θ=56.3° about the y-axis is needed to bring 4002to z=0. It should be appreciated that the appropriate direction (+or −)of the rotation angle to plug into the rotation matrix can be confusing.In some embodiments, it is beneficial to draw the plane of the rotationwith the rotation axis coming out of the plane contained in the pagesurface (for example, the right-hand rule can provide a suitableorientation), then a counterclockwise rotation is positive and aclockwise rotation is negative. In the foregoing example, the axis wasgoing into the page surface, thus a clockwise rotation was positive.

FIGS. 8A-8C illustrates an alternative representation of two dimensionalrepresentations for rotations about the axis, depicting how each planecan be drawn for counterclockwise positive and clockwise negative inaccordance with some embodiments of the invention. As shown, FIG. 8Aillustrates an alternative representation of a two dimensionalrepresentation for rotation about an X-axis. FIG. 8B illustrates analternative representation of a two dimensional representation forrotation about a Y-axis. FIG. 8C illustrates an alternativerepresentation of a two dimensional representation for rotation about aZ-axis

In some embodiments, to rotate the rigid body about the y-axis so that4002 is in the x-y plane (z=0):

$\theta_{y} = {+ {\tan^{- 1}\left( \frac{4002_{z}}{4002_{x}} \right)}}$

In some embodiments, to rotate the rigid body about the z-axis so that4002 is at y=0,

$\theta_{z} = {- {\tan^{- 1}\left( \frac{4002_{y}}{4002_{x}} \right)}}$

In some embodiments, to rotate the rigid body about the x-axis so that4003 is at z=0:

$\theta_{x} = {- {\tan^{- 1}\left( \frac{4003_{z}}{4003_{y}} \right)}}$

As described herein, the example method to transform markers 4001, 4002,4003 as close as possible to the reference frame can comprise; 1)translate the rigid body so that 4001 is at the origin (0, 0, 0), and 2)rotate about the y-axis so that 4002 is in the x-y plane (i.e., z=0),and 3) rotate about the z-axis so that 4002 is at y=0, x coordinatepositive, and 4). rotate about the x-axis so that 4003 is at z=0, ycoordinate positive. In other embodiments, a method to reach the samereference can comprise: 1) translate the rigid body so that 4001 is atthe origin (0, 0, 0), and 2) rotate about the x-axis so that 4002 is inthe x-y plane (i.e., z=0), and 3) rotate about the z-axis so that 4002is at y=0, x coordinate positive, 4) rotate about the x-axis so that4003 is at z=0, y coordinate positive. It should be appreciated thatthere are other possible methods and related actions, both in thereference frame chosen and in how the rigid body is manipulated to getit there. The described method is simple, but does not treat markersequally. The reference frame requires 4001 to be restricted the most(forced to a point), 4002 less (forced to a line), and 4003 the least(forced to a plane). As a result, errors from noise in markers aremanifested asymmetrically. For example, consider a case where in acertain frame of data, noise causes each of the three markers to appearfarther outward than they actually are or were (represented by 4001 a,4002 a, and 4003 a) when the reference frame was stored (as depicted inFIG. 9.)

In some embodiments, when the transformations are done to align theapparent markers “as close as possible” to their stored referenceposition, they will be offset. For example, when the stored point ofinterest is added, it will be misplaced in a direction on which markerwas chosen as 4001 in the algorithm (see 4003, 4003 a and 4002, 4002 afor example in FIG. 10).

Some embodiments provide additional or alternative methods for trackingpoints of interest that can involve more symmetrical ways of overlayingthe actual marker positions with the stored reference positions. Forexample, in some embodiments, for three markers 4001, 4002, 4003, atwo-dimensional fitting method typically utilized in zoology can beimplemented. (See, e.g., Sneath P. H. A., “Trend-surface analysis oftransformation grids,” J. Zoology 151, 65-122 (1967)). The method caninclude a least squares fitting algorithm for establishing a referenceframe and transforming markers to lie as close as possible to thereference. In this case, the reference frame is the same as describedearlier except that the common mean point (hereinafter referred to as“CMP”) is at the origin instead of marker 4001. In some embodiments, theCMP after forcing the markers into the x-y plane is defined in thefollowing equation (and can be represented in FIG. 11):

${CMP} = {\begin{bmatrix}\overset{\_}{x} \\\overset{\_}{y} \\0\end{bmatrix} = \begin{bmatrix}{\left( {{M1_{x}} + {M2_{x}} + {M3_{x}}} \right)/3} \\{\left( {{M1_{y}} + {M2_{y}} + {M3_{y}}} \right)/3} \\0\end{bmatrix}}$

In some embodiments, for the markers to be centered around CMP, themarkers can be translated by subtracting the CMP from 4001, 4002, and4003. It should be noted that the point of interest being tracked is notincluded in determining CMP_(ref).

In some embodiments, the method to transform markers as close aspossible to this reference frame can comprise; 1) translating the rigidbody so that 4001 is at the origin (0, 0, 0), and 2) rotating about they-axis so that 4002 is in the x-y plane (i.e., z=0), and 3) rotatingabout the z-axis so that 4002 is at y=0, x coordinate positive into thex-ray plane, and 4) rotating about the x-axis so that 4003 is at z=0, ycoordinate positive, and finally 5) calculate the CMP for the markers4001, 4002, 4003 and translating the rigid body so that the CMP is atthe origin (i.e., subtract the CMP from each point transformed). In someembodiments, steps 1-5 are done for the original set of markers forwhich the position of the point of interest was known and for the newset for which you are adding the point of interest. A further step canbe included for the new set, for example, 6) rotate about the z-axis tobest overlay the stored reference markers. In some embodiments, therotation angle θ is found using the formula from Sneath:

${\tan\theta} = \frac{{\sum{x_{{pos}2}y_{ref}}} - {\sum{x_{ref}y_{pos2}}}}{{\sum{x_{ref}x_{pos2}}} + {\sum{y_{ref}y_{pos2}}}}$

In some embodiments, if M1, M2, M3 denote the stored reference markersand M′1, M′2, M′3 denote the position being tracked in this data-frame,the equation can be written:

$\tan^{- 1} = \left\lbrack \frac{\begin{matrix}{\left( {{M^{\prime}1_{x}M1_{y}} + {M^{\prime}2_{x}M2_{y}} + {M^{\prime}3_{x}M3_{y}}} \right) -} \\\left( {{M1_{x}M^{\prime}1_{y}} + {M2_{x}M^{\prime}2_{y}} + {M3_{x}M^{\prime}3_{y}}} \right)\end{matrix}}{\begin{matrix}{\left( {{M1_{x}M^{\prime}1_{x}} + {M2_{x}M^{\prime}2_{x}} + {M3_{x}M^{\prime}3_{x}}} \right) +} \\\left( {{M1_{y}M^{\prime}1_{y}} + {M2_{y}M^{\prime}2_{y}} + {M3_{y}M^{\prime}3_{y}}} \right)\end{matrix}} \right\rbrack$

It should be noted that this rotation angle can be small (e.g., smallerthan about 1°). In some embodiments, after the markers 4001, 4002, 4003are overlaid, some embodiments of the invention can include adding thepoint of interest then transforming the point of interest back to itstrue present location in the current frame of data. In some embodiments,to transform back, negative values saved from the forward transformationsteps 1-6 as discussed above can be utilized. That is, for instance, gofrom step 6 to step 5 by rotating by negative θ, go from step 5 to step4 by adding the CMP, etc.)

In some embodiments, using this least-squares algorithm, noise ismanifested more symmetrically and the point of interest will probably becalculated to be closer to its actual location. This can be illustratedin FIG. 12, which illustrates a depiction of results of applying a leastsquares fitting algorithm for establishing a reference frame andtransforming markers 4001, 4002, 4003 as shown in FIG. 11 includingnoise. Regardless of which method is used, it can be beneficial tomonitor the error between the marker locations at a given frame of dataand the reference marker locations. In some embodiments, the method caninclude calculating and sum the vector distances of each marker andreport the value in mm.

FIG. 13 for example illustrates a depiction of error calculation forreference frame markers in accordance with some embodiments of theinvention. In some embodiments, by continuously displaying this errorvalue, the agent can be alerted if markers 4001, 4002, 4003 have becomepartially obscured, or if a marker 4001, 4002, 4003 is no longersecurely or rigidly attached to the rigid body. In some embodiments,when performing a best fit on more than 3 markers, they cannot be forcedinto a plane, and therefore the problem becomes much more difficult. Insome embodiments, one solution is to inspect all or nearly all possibletriangles formed by groups of 3 markers 4001, 4002, 4003 and evaluatewhich one gives the least standard deviation of the angles of thevertices. See Chèze L, Fregly B. J., Dimnet J, :Technical note: Asolidification procedure to facilitate kinematic analyses based on videosystem data,” Journal of Biomechanics 28(7), 879-884 (1995). In someother embodiments, the method can include calculating a least squaresfit of the vertices of the geometric shape, requiring iteration toperform matrix decomposition (i.e., Newton-Raphson method). For example,see Veldpaus F E, Woltring H J, Dortmans L J M G, ‘A least-squaresalgorithm for the equiform transformation from spatial markerco-ordinates’, Journal of Biomechanics 21(1), 45-54 (1988).

In some embodiments, when tracking 3D movement of a rigid body (forexample, a robot 15 end-effectuator 30 or a targeted bone) using anarray of 3 tracking markers 4001, 4002, 4003 that are rigidly attachedto the rigid body, one example method for quantifying motion can includedetermining the transformations (translation and rotations) for themovement from a first (neutral) position (defined here as “A”) to second(current frame) position (herein referred to as “B”). In someembodiments, it may be convenient to describe the rotations as a threeby three orientation matrix (direction cosines) of the rigid body in theposition B, and to treat the three translation values as a 3×1 vectorcontaining the x, y, z coordinates of the origin of the position Acoordinate system transformed to position B. In some embodiments, thedirection cosine matrix is a 3×3 matrix, the columns of which containunit vectors that originally were aligned with the x, y, and z axes,respectively, of the neutral coordinate system. In some embodiments, tobuild a direction cosine matrix, a 3×3 matrix, A, can be defined in amanner that its columns are unit vectors, i, j, and k, aligned with thex, y, and z axes, respectively:

$A = {\begin{bmatrix}i_{x} & j_{x} & k_{x} \\i_{y} & j_{y} & k_{y} \\i_{z} & j_{z} & k_{z}\end{bmatrix} = \begin{bmatrix}1 & 0 & 0 \\0 & 1 & 0 \\0 & 0 & 1\end{bmatrix}}$

Upon or after rotations of the coordinate system occur, in someembodiments, the new matrix (which is the direction cosine matrix, A′)is as follows, where the unit vectors i′, j′, and k′ represent the neworientations of the unit vectors that were initially aligned with thecoordinate axes:

$A^{\prime} = \begin{bmatrix}i_{x}^{\prime} & j_{x}^{\prime} & k_{x}^{\prime} \\i_{y}^{\prime} & j_{y}^{\prime} & k_{y}^{\prime} \\i_{z}^{\prime} & j_{z}^{\prime} & k_{z}^{\prime}\end{bmatrix}$

In some embodiments, to determine the direction cosines and translationvector, the origin and unit vectors can be treated as aligned with thecoordinate axes as four tracked points of interest in the mannerdescribed herein. For example, if the origin (o) and three unit vectors(i, j, k) are aligned with the coordinate axes, they are treated asvirtual tracked points of interest with coordinates of:

$o = {\left. \begin{bmatrix}0 \\0 \\0\end{bmatrix}\rightarrow i \right. = {\left. \begin{bmatrix}1 \\0 \\0\end{bmatrix}\rightarrow j \right. = {\left. \begin{bmatrix}0 \\1 \\0\end{bmatrix}\rightarrow k \right. = \begin{bmatrix}0 \\0 \\1\end{bmatrix}}}}$

In some embodiments, these points of interest can provide the directioncosines and translation for the movement when moved along with the threemarkers from position A to position B. In some embodiments, it may beconvenient to implement (for example execute) the method for moving thevirtual points to these four points placed into a 3×4 matrix, P.

In some embodiments, the matrix is as follows in position A:

$P = {\begin{bmatrix}o_{x} & i_{x} & j_{x} & k_{x} \\o_{y} & i_{y} & j_{y} & k_{y} \\o_{z} & i_{z} & j_{z} & k_{z}\end{bmatrix} = \begin{bmatrix}0 & 1 & 0 & 0 \\0 & 0 & 1 & 0 \\0 & 0 & 0 & 1\end{bmatrix}}$

In some embodiments, the matrix is as follows in position B:

$P^{\prime} = {\begin{bmatrix}a_{x} & b_{x} & c_{x} & d_{x} \\a_{y} & b_{y} & c_{y} & d_{y} \\a_{z} & b_{z} & c_{z} & d_{z}\end{bmatrix} = \begin{bmatrix}o_{x}^{\prime} & {i_{x}^{\prime} + o_{x}^{\prime}} & {j_{x}^{\prime} + o_{x}^{\prime}} & {k_{x}^{\prime} + o_{x}^{\prime}} \\o_{y}^{\prime} & {i_{y}^{\prime} + o_{y}^{\prime}} & {j_{y}^{\prime} + o_{y}^{\prime}} & {k_{y}^{\prime} + o_{y}^{\prime}} \\o_{z}^{\prime} & {i_{z}^{\prime} + o_{z}^{\prime}} & {j_{z}^{\prime} + o_{z}^{\prime}} & {k_{z}^{\prime} + o_{z}^{\prime}}\end{bmatrix}}$

In some embodiments, after movement, the direction cosine matrix is

$A^{\prime} = {\begin{bmatrix}i_{x}^{\prime} & j_{x}^{\prime} & k_{x}^{\prime} \\i_{y}^{\prime} & j_{y}^{\prime} & k_{y}^{\prime} \\i_{z}^{\prime} & j_{z}^{\prime} & k_{z}^{\prime}\end{bmatrix} = \begin{bmatrix}{b_{x} - a_{x}} & {c_{x} - a_{x}} & {d_{x} - a_{x}} \\{b_{y} - a_{y}} & {c_{y} - a_{y}} & {d_{y} - a_{y}} \\{b_{z} - a_{z}} & {c_{z} - a_{z}} & {d_{z} - a_{z}}\end{bmatrix}}$

In some embodiments, the vector o′ represents the new position of theorigin. In some embodiments, after moving the three markers 4001, 4002,4003 from position A to position B, and bringing the four points (as a3×4 matrix) along with the three markers 4001, 4002, 4003, thetranslation of the origin is described by the first column. Further, insome embodiments, the new angular orientation of the axes can beobtained by subtracting the origin from the 2^(nd), 3^(rd), and 4^(th)columns. These methods should be readily apparent from the followinggraphic representation in FIG. 14, which illustrates a graphicalrepresentation of methods of tracking three dimensional movement of arigid body.

In some embodiments, if more than three markers 4001, 4002, 4003 areutilized for tracking the movement of a rigid body, the same method canbe implemented repeatedly for as many triads of markers as are present.For example, in a scenario in which four markers, M1, M2, M3, and M4,are attached to the rigid body, there can be four triads: those formedby {M1, M2, M3}, {M1, M2, M4}, {M1, M3, M4}, and {M2, M3, M4}. In someembodiments, each of these triads can be used independently in themethod described hereinbefore in order to calculate the rigid bodymotion. In some embodiments, the final values of the translations androtations can then be the average of the values determined using thefour triads. In some embodiments, in the alternative or in addition,other methods for achieving a best fit when using more than 3 markersmay be used.

In some embodiments, when tracking with four markers, in a scenario inwhich one of the four markers becomes obscured, it can desirable toswitch to tracking the rigid body with the remaining three markersinstead of four. However, this change in tracking modality can cause asudden variation in the results of one or more calculations utilized fortracking. In some embodiments, the variation can occur because thesolution from the one remaining triad may be substantially differentthan the average of 4 triads. In some embodiments, if using the trackedposition of the rigid body in a feedback loop to control the position ofa robot 15 end-effectuator, the sudden variation in results of thecalculation can be manifested as a physical sudden shift in the positionof the robot 15 end-effectuator 30. In some embodiments, this behavioris undesirable because the robot 15 is intended to hold a guide tube 50steady with very high accuracy.

Some embodiments include an example method for addressing the issue ofsudden variation that occurs when one of the four markers M1, M2, M3, M4is blocked, thereby causing the position to be calculated from a singletriad instead of the average of four triads, can include reconstructingthe blocked marker as a virtual marker. In some embodiments, toimplement such reconstructing step with high accuracy, the most recentframe of data in which all four markers M1, M2, M3, M4 are visible canbe retained substantially continuously or nearly continuously (forexample in a memory of a computing device implementing the subjectexample method). In some embodiments, if all four markers M1, M2, M3, M4are in view, the x-axis, y-axis, and z-axis coordinates of each of thefour markers M1, M2, M3, and M4 are stored in computer 100 memory. Itshould be appreciated that in some embodiments, it may unnecessary tolog all or substantially all frames and is sufficient to overwrite thesame memory block with the most recent marker coordinates from a fullvisible frame. Then, in some embodiments, at a frame of data in whichone of the four markers M1, M2, M3, and M4 is lost, the lost marker'sposition can be calculated based on the remaining triad, using theexample method described herein for remaining three markers. That is,the triad (the three visible markers) is transformed to a reference. Thestored set of markers is then transformed to the same reference usingthe corresponding triad with the fourth marker now acting as a virtuallandmark. The recovered position of the lost fourth marker can then betransformed back to the current position in space using the inverse ofthe transformations that took it to the reference position. In someembodiments, after the lost marker's position is reconstructed,calculation of the rigid body movement can be performed as before, basedon the average of the fourth triads, or other best fit method fortransforming the rigid body from position A to position B.

In some embodiments, an extension to the methods for reconstructingmarkers 720 is to use multiple ambiguous synchronized lines of sight viamultiple cameras 8200 tracking the same markers 720. For example, two ormore cameras 8200 (such as Optotrak® or Polaris®) could be set up fromdifferent perspectives focused on the tracking markers 720 on thetargeting fixture 690 or robot 15. In some embodiments, one camera unitcould be placed at the foot of a patient's bed, and another could beattached to the robot 15. In some embodiments, another camera unit couldbe mounted to the ceiling. In some embodiments, when all cameras 8200substantially simultaneously view the markers 720, coordinates could betransformed to a common coordinate system, and the position of any ofthe markers 720 would be considered to be the average (mean) of thatmarker's three dimensional position from all cameras used. In someembodiments, even with extremely accurate cameras, an average is neededbecause with system noise, the coordinates as perceived from differentcameras would not be exactly equal. However, when one line of sight isobscured, the lines of sight from other cameras 8200 (where markers 720can still be viewed) could be used to track the robot 15 and targetingfixture 690. In some embodiments, to mitigate twitching movements of therobot 15 when one line of sight is lost, it is possible that the marker720 positions from the obscured line of sight could be reconstructedusing methods as previously described based on an assumed fixedrelationship between the last stored positions of the markers 720relative to the unobstructed lines of sight. Further, in someembodiments, at every frame, the position of a marker 720 from camera 1relative to its position from camera 2 would be stored; then if camera 1is obstructed, and until the line of sight is restored, this relativeposition is recalled from computer memory (for example in memory of acomputer platform) and a reconstruction of the marker 720 from camera 1would be inserted based on the recorded position of the marker fromcamera 2. In some embodiments, the method could compensate for temporaryobstructions of line of sight such as a person standing or walking infront of one camera unit.

In certain embodiments, when a marker M1, M2, M3, M4 is lost but issuccessfully reconstructed in accordance with one or more aspectdescribed herein, the marker that has been reconstructed can be renderedin a display device. In one example implementation, circles representingeach marker can be rendered graphically, coloring the circles formarkers M1, M2, M3, M4 that are successfully tracked in green, markersM1, M2, M3, M4 that are successfully reconstructed in blue, and markersM1, M2, M3, M4 that cannot be tracked or reconstructed in red. It shouldbe appreciated that such warning for the agent can serve to indicatethat conditions are not optimal for tracking and that it is prudent tomake an effort for all four tracking markers to be made fully visible,for example, by repositioning the cameras or standing in a differentposition where the marker is not blocked. Other formats and/or indiciacan be utilized to render a virtual marker and/or distinguish suchmarker from successfully tracked markers. In some embodiments, it ispossible to extend the method described herein to situations relying onmore than four markers. For example, in embodiments in which fivemarkers are utilized on one rigid body, and one of the five markers isblocked, it is possible to reconstruct the blocked marker from theaverage of the four remaining triads or from another method for best fitof the 4 remaining markers on the stored last visible position of all 5markers. In some embodiments, once reconstructed, the average positionof the rigid body is calculated from the average of the 10 possibletriads, {M1, M2, M3}, {M1, M2, M4}, {M1, M2, M5}, {M1, M3, M4}, {M1, M3,M5}, {M1, M4, M5}, {M2, M3, M4}, {M2, M3, M5}, {M2, M4, M5}, and {M3,M4, M5} or from another method for best fit of 5 markers from position Ato position B.

As discussed above, in some embodiments, the end-effectuator 30 can beoperatively coupled to the surgical instrument 35. This operativecoupling can be accomplished in a wide variety of manners using a widevariety of structures. In some embodiments, a bayonet mount 5000 is usedto removably couple the surgical instrument 35 to the end-effectuator 30as shown in FIG. 15. For example, FIG. 15 shows a perspective viewillustrating a bayonet mount 5000 used to removably couple the surgicalinstrument 35 to the end-effectuator 30. In some embodiments, thebayonet mount 5000 securely holds the surgical instrument 35 in placewith respect to the end-effectuator 30, enabling repeatable andpredictable location of operational edges or tips of the surgicalinstrument 35.

In some embodiments, the bayonet mount 5000 can include ramps 5010 whichallow identification of the surgical instrument 35 and ensure compatibleconnections as well. In some embodiments, the ramps 5010 can be sizedconsistently or differently around a circumference of the bayonet mount5000 coupled to or integral with the surgical instrument 35. In someembodiments, the differently sized ramps 5010 can engage complementaryslots 5020 coupled to or integral with the end-effectuator 30 as shownin FIG. 15.

In some embodiments, different surgical instruments 35 can includedifferent ramps 5010 and complementary slots 5020 to uniquely identifythe particular surgical instrument 35 being installed. Additionally, insome embodiments, the different ramps 5010 and slots 5020 configurationscan help ensure that only the correct surgical instruments 35 areinstalled for a particular procedure.

In some embodiments, conventional axial projections (such as those shownin U.S. Pat. No. 6,949,189 which is incorporated herein as needed toshow details of the interface) can be mounted to or adjacent the ramps5010 in order to provide automatic identification of the surgicalinstruments 35. In some embodiments, other additional structures can bemounted to or adjacent the ramps 5010 in order to provide automaticidentification of the surgical instruments 35. In some embodiments, theaxial projections can contact microswitches or a wide variety of otherconventional proximity sensors in order to communicate the identity ofthe particular surgical instrument 35 to the computing device or otherdesired user interface. Alternatively, in some other embodiments of theinvention, the identity of the particular surgical instrument 35 can beentered manually into the computing device or other desired userinterface.

In some embodiments, instead of a targeting fixture 690 consisting of acombination of radio-opaque 730 and active markers 720, it is possibleto register the targeting fixture 690 through an intermediatecalibration. For example, in some embodiments, an example of such acalibration method could include attaching a temporary rigid plate 780that contains radio-opaque markers 730, open mounts 785 (such as snaps,magnets, Velcro, or other features) to which active markers 720 canlater be attached in a known position. For example, see FIGS. 16A-Fwhich depict illustrations of targeting fixtures 690 coupled to a spineportion 19 of a patient 18 in accordance with one embodiment of theinvention). The method can then include scanning the subject (using forexample CT, MRI, etc.), followed by attaching a percutaneous tracker 795such as those described earlier or other array of 3 or more activemarkers 720 rigidly affixed to the anatomy 19 as for example in FIG.16B, and then attaching active markers 720 to the temporary plate 780 inthe known positions dictated by the snaps, magnets, Velcro, etc., asillustrated in FIG. 16C. In some embodiments, a further step can includeactivating the cameras 8200 to read the position of the tracker 795rigidly affixed to the anatomy 19 at the same time as the active markers720 on the temporary plate 780. This step establishes the position ofthe active markers 720 on the temporary plate 780 relative to theradio-opaque markers 730 on the temporary plate 780 as well as thepositions of the active markers 720 on the tracker 795 relative to theactive markers 720 on the temporary plate 780, and therefore establishesthe position of the anatomy relative to the active markers 720 on thetracker 795. The temporary plate 780 can be removed (as illustrated inFIG. 16D), including the active markers 720 and radio-opaque markers730. These markers are no longer needed because registration has beenperformed relative to the active markers on the rigidly affixed tracker795.

In some alternative embodiments, variants of the order of the abovedescribed steps may also be used. For instance, the active markers 720could already be attached at the time of the scan. This method hasadvantage that the radio-opaque markers 730 can be positioned close tothe anatomy of interest without concern about how they are attached tothe tracker 795 with active markers 720. However, it has thedisadvantage that an extra step is required in the registration process.In some embodiments, a variant of this method can also be used forimproved accuracy in which two trackers of active markers 720 areattached above and below the region of interest. For example, a trackerrostral to the region of interest (shown as 795) could be a spinousprocess 2310 clamp in the upper lumbar spine and a tracker caudal to theregion of interest (shown as 800) could be a rigid array of activemarkers 720 screwed into the sacrum (see for example FIG. 16E). Aftercalibration, the temporary plate 780 is removed and the area between thetwo trackers (within the region 805) is registered (see for example FIG.16F).

Some embodiments can include methods for transferring registration. Forexample, a registration performed to establish the transformations inorder to transpose from a medical image coordinate system (such as theCT-scanned spine) to the coordinate system of the cameras, can later betransferred to a different reference. In the example described in theabove related to FIGS. 16A-16F, a temporary fixture 780 withradio-opaque markers 730 and active markers 720 is placed on the patient18 and registered. Then, a different fixture 795 is attached to thepatient with active markers 720 only. Then the cameras (for example,camera 8200) are activated, and the active markers 720 on the temporaryplate 780 are viewed simultaneously with the active markers 720 on thenew tracking fixture 795. The necessary transformations to get from thetemporary markers (those on the temporary plate 780) to the new markers(i.e. the markers on fixture 795) are established, after which thetemporary plate 780 can be removed. In other words, the registration wastransferred to a new reference (fixture 795). In some embodiments, itshould be possible to repeat this transferal any number of times.Importantly, in some embodiments, one registration can also beduplicated and transferred to multiple references. In some embodiments,transferal of registration to multiple references would provide a meansfor tracking relative motion of two rigid bodies. For example, atemporary targeting fixture may be used to register the anatomy to thecameras 8200. Then, two new targeting fixtures may be placed on separatebones that are both included in the medical image used for registration.If the registration from the temporary targeting fixture is transferredto both of the new targeting fixtures, both of these bones may betracked simultaneously, and the position of the robot end effectuator 30or any other tracked probe or tool relative to both bones can bevisualized. If one bone then moves relative to the other, the endeffectuator's position would be located differently relative to the twotrackers and the two medical images (for example, see FIGS. 17B-17Dshowing the two trackers 796 and 797 positioned on a portion of spine19).

In some embodiments, after registration is transferred to both trackers796, 797, the robot end effectuator 30 may be perceived by both trackers796, 797 to be positioned as shown. In some embodiments, it is possiblethat one of the bones to which a tracker is mounted moves relative tothe other, as shown in exaggerated fashion in FIG. 17C. In someembodiments, if the end effectuator 30 is considered fixed, theperception by the tracking system and software would be that the spine19 was positioned in two possible relative locations, depending on whichtracker is followed (see for example, the representation in FIG. 17D).Therefore, in some embodiments, by overlaying representations of bothmedical images, it becomes possible to visualize the relative movementof the bones on which the trackers 796, 797 are attached. For example,instead of displaying the re-sliced medical image on the screen andshowing the position of the robot end effectuator 30 relative to thatimage, two re-sliced medical images could be overlapped (each allowingsome transparency) and simultaneously displayed, showing one positionwhere the robot end effectuator currently is positioned relative to bothimages (see FIGS. 17E-17F). However, the duplication of bones would makethe representation cluttered, and therefore in some embodiments, it canbe possible to automatically or manually segment the medical image suchthat only bones that do not move relative to a particular tracker 796,797 are represented on the image (shown in FIG. 17E with the bones 19 ahighlighted as in relation to bone regions meaningful to tracker 796with regions 19 b faded, and FIG. 17F with the bones 19 a highlighted inrelation to bone regions meaningful to tracker 797, with regions 19 bfaded). Segmenting would mean hiding, fading, or cropping out theportion of the 3D medical image volume that the user does not want tosee (represented as the faded regions 19 b in FIGS. 17E and 17F).

In some embodiments, segmentation could involve identifying borderingwalls on the 3D image volume or bordering curves on 2D slices comprisingthe medical image. In some embodiments, by segmenting simple six-sidedvolumes, enough separation of critical elements could be visualized forthe task. In some embodiments, bones on the slice from a CT scansdepicted in FIGS. 17G and 17H are shown with segmentation into region 20a, corresponding to the bone regions 19 a referred to in FIGS. 17E and17F, and 20 b, corresponding to region 19 b. In some embodiments, theregions 20 a and 20 b can be represented in different shades of color(for example, blue for 20 a and yellow for 20 b). Furthermore, as shown,the segmentation as displayed is depicted to proceed in and out of thepage to include the entire CT volume. Moreover, although it goes rightthrough the disc space, this segmentation cuts through one spinousprocess 2310 in the image in FIG. 17G, and does not follow the facetjoint articulations to segment independently moving bones, as shown in adifferent slice represented in FIG. 17H. However, the re-sliced imagesof these overlapped volumes should still be useful when placing, forexample, pedicle screws since the pedicles are properly segmented in theimages.

An example of transferal of registration to multiple trackers includesconventional pedicle screw placement followed by compression ordistraction of the vertebrae. For example, if pedicle screws are beingplaced at lumbar vertebrae L4 and L5, a tracker could be placed on L3and registered. In some embodiments, conventional pedicle screws couldthen be placed at L4 and L5, with extensions coming off of each screwhead remaining after placement. In some embodiments, two new trackers(for example, trackers substantially similar to 796, 797) could then beattached to the extensions on the screw heads, one at L4 and one at L5.Then, the registration could be transferred to both of these newtrackers and a tracker at L3 could be removed or thereafter ignored. Insome embodiments, if the medical image is segmented so that L4 androstral anatomy is shown relative to the tracker on L4 (while L5 andcaudal anatomy is shown relative to the tracker on L5), then it can bepossible to see how the L4 and L5 vertebrae move relative to oneanother, as compressive or distractive forces are applied across thatjoint. In some embodiments, such compression or distraction might beapplied by the surgeon when preparing the disc space for an inter-bodyspacer, or inserting the spacer, or when compressing the vertebraetogether using a surgical tool after the inter-body spacer is in place,and before locking the pedicle screw interconnecting rod.

In some embodiments, if there is snaking of the spine, for example, whenconventional screws are driven in place or the surgeon applies a focalforce on one portion of the spine, the two marker trees will move(illustrated as 795 a for tracker 795 and 800 a for tracker 800) bydifferent amounts and to different orientations (illustrated in FIG.17A). The altered orientations and positions of the trackers 795, 800can be used to calculate how the spine has snaked and adjust theperceived position of the robot 15 or probe to compensate. In someembodiments, because there are multiple degrees of freedom of thevertebrae, knowledge of how the two trackers' orientations shift doesnot allow a single unique solution. However, it can be assumed that thebending is symmetrical among all the vertebrae to calculate the newposition, and even if this assumption is not perfect, it should providea reasonably accurate solution. In some embodiments, experimentstracking how cadaveric spines respond to focal forces can be used tocollect data that will help to predict how the two ends of the lumbarspine would respond during particular types of external loading.

In some embodiments, it is possible to use the same surgical robot 15already described for navigation with 3D imaging in a different settingwhere only 2 fluoroscopic views are obtained. In this instance, thesurgical robot 15 will be able to accurately move to a desired positionthat is pre-planned on these two fluoroscopic views. Since the twofluoroscopic views can represent views to which the surgeon orradiologist is already accustomed, planning trajectories on these viewsshould be straightforward. In obtaining the fluoroscopic views, a methodis needed to establish the position of the coordinate system of theanatomy relative to the robot's 15 coordinate system. In someembodiments, a way to fulfill this registration is to obtain thefluoroscopic views while a targeting fixture 690 that includes featuresthat are identifiable on the fluoroscopic images is attached to thepatient 18. For example, FIG. 18 shows an example of a fixture for usewith fluoroscopic views in accordance with one embodiment of theinvention. In some embodiments, the targeting fixture 690 as shown caninclude features that will appear on 2 fluoroscopic views and activemarkers 720 for real-time tracking. This targeting fixture 690 hasproperties that will aid in the ability to set up the coordinate systemof the anatomy from the two fluoroscopic images. For example, in someembodiments, the posts 75 as shown are symmetrically spaced around theframe 700 so that posts 75 and/or their embedded markers 730 wouldoverlay on an x-ray image. That is, if there is no parallax, two posts75 in an aligned position would appear as a single line segment insteadof two, or two posts 75, each with two embedded radio-opaque markers730, would appear as two dots instead of four dots on an x-ray image.These features allow and facilitate the patient 18 or fluoroscopymachine's position to be adjusted until such overlapping is achieved.Similarly, from top or bottom view, the posts 75 and/or their embeddedmarkers 730 would overlap, with a single post appearing as a dot insteadof a line segment or two embedded markers 730 in one post appearing asone dot instead of two once the fluoroscopy machine and patient 18 areadjusted to be aligned as desired. In some embodiments, the posts 75 maybe designed to be temporarily inserted (i.e., they are present duringthe scan but are later unplugged from the frame during the procedure sothey are not in the way of the user). In some embodiments, the activemarkers 720 are necessary for later tracking but do not necessarily needto be present during the scan as long as they can be attached withprecision to a known position on the frame 700 relative to theradio-opaque makers 730. For example, in some embodiments, conventionalsockets on the fixture 690 could later allow the active markers 720 tobe snapped in to a location dictated by the manufacturing of the frame700 or calibrated using a digitizing probe. Furthermore, note that thegoal is not necessarily to get perfect lateral and anteroposterioranatomical views of the spine or other anatomy. The goal is to getalignment of the fixture 700 on the x-ray view. Although it may bebeneficial in understanding what it being visualized to also achievealignment with the anatomical planes, it is unnecessary forregistration. An example of how the targeting fixture 690 might appearon anteroposterior or “A-P” and lateral x-rays when affixed to thepatient's back but not yet aligned with the x-ray projection is shown inFIGS. 19A-19B.

In some embodiments, after adjusting the position of the patient 18 andfluoroscopy unit, an overlay with good certainty may be obtained forimages with radio-opaque markers 730. FIGS. 20A-20B for exampleillustrates expected images on anteroposterior and lateral x-rays of thespine with a well aligned fluoroscopy (x-ray) machine in accordance withone embodiment of the invention. As shown, the fluoroscopic images donot need the frame 700 to be positioned exactly aligned with the anatomyor rotated to be vertical and horizontal. In some embodiments, thefluoroscopically obtained images are not required to have the correctaspect ratio such that the image properly represents a calibratedcoordinate system. In some embodiments, it is possible to rescale theimage to adjust the aspect ratio using known distances between posts 75or between markers 730, x-ray visible lengths of posts 75, or assumingthe image should be perfectly circular or square. These distances areknown in advance of obtaining the images by the manufacturing process,or by calibration using a digitizing probe or other means. In someembodiments, provided parallax is considered, the ratio of knowninter-marker distances can be compared to the ratio of inter-markerdistances measured on planar images and used to scale the planar imageto achieve the correct aspect ratio. In some embodiments, it is notnecessary to rescale the image, but it may help the user to bettervisualize the image and anatomy when it is displayed in the appropriateaspect ratio. In some embodiments, the comparison can also be used todetermine the number of pixels per mm on the image for use indetermining relative position of radio-opaque markers 730 and plannedtrajectory tip and tail. In some embodiments, rescaling facilitatesequations for mapping between 2D and 3D space because the pixels per mmin the x and y direction are the same value.

In some embodiments, after obtaining two images, the two images can beused to construct a 3D Cartesian coordinate system because theyrepresent images of the same thing (the fixture) from two orthogonalviews. For example, the A-P image could be used to represent the X-Zplane, and the lateral image could be used to represent the Y-Z plane.Radio-opaque markers 730 on the A-P image have known x-axis and z-axiscoordinates (as recorded from the manufacturing process or bycalibration using a digitizing probe or other means), and the sameradio-opaque markers 730 have known y-axis and z-axis coordinates on thelateral image. Therefore, in some embodiments, the x-axis, y-axis, andz-axis coordinates of the markers 730 can be found on the two images,and the positions of the anatomy and planned trajectories relative tothese reference points can be related to these reference positions. Insome embodiments, the mapping of a point from 3D space to the 2D imageand vice versa can be performed knowing the constant mm per pixel, C, oncoronal or sagittal images, and multiplying or dividing points by theseconstants if the center of the image and coordinate system have beenshifted to overlap.

FIGS. 21A-21B illustrates expected images on anteroposterior and lateralx-rays of the spine with a well aligned fluoroscopy (x-ray) machine inaccordance with one embodiment of the invention. As shown, FIGS. 21A-21Binclude overlaid computer-generated graphical images showing the plannedtrajectory (red 6001) and the current actual position of the robot 15end-effectuator 30 (light blue 6003). The red circle in 6001 is providedfor the user to identify the tail of the planned trajectory (as opposedto the tip). In other embodiments, the line segment could have differentcolored ends or different shapes on each end (pointed vs. blunt) fordistinguishing tip from tail.

In some embodiments, assuming the A-P x-ray represents the X-Z plane andthe lateral x-ray represents the Y-Z plane, the algorithm for planning atrajectory and relating this planned trajectory to the robot 15coordinate system can include the following steps; 1). Draw a line onthe A-P and lateral x-ray views representing where the desiredtrajectory should be positioned (see for example FIGS. 21A-21B). In someembodiments, the next step can include; 2). from the A-P view, find theX and Z coordinates of the reference opaque markers and of the tip andtail of the desired trajectory, and 3). from the lateral view, find theY and Z coordinates of the reference opaque markers and of the tip andtail of the desired trajectory, and 4). based on the known coordinatesof the active markers relative to the opaque markers, transform the X,Y, Z coordinates of the tip/tail into the coordinate system of theactive markers. In some embodiments, the method can include store thelocations of tip and tail in this coordinate system in computer 100memory for later retrieval. In some embodiments, the next steps of themethod can include; 5). at any frame in real time, retrieve the activemarker 720 locations in the coordinate system of the cameras 8200, and6). based on the stored coordinates of the tip and tail relative to theactive markers 720 and the current location of the active markers 720 inthe coordinate system of the cameras 8200, calculate the currentlocation of the desired tip and tail in the coordinate system of thecameras 8200. In some embodiments, the next steps of the method caninclude; 7). transform the active marker 720 locations and thetrajectory tip/tail locations into the coordinate system of the robot 15using methods described before in which markers on the robot 15 areutilized as references, and 8). send the robot 15 to the desiredtip/tail locations using methods described previously.

In some embodiments, while the robot 15 moves to position itself in thedesired orientation and position, it is possible to overlay a graphicalrepresentation of the current location of the robot 15 on thefluoroscopic images by a method that can include; 1). retrieve currentlocation of the robot 15 guide tube 50 in the coordinate system of thecameras 8200 based on active markers 720 attached to the robot, and 2).transform the guide tip and tail to the coordinate system of the medicalimages based on the locations of active markers on the targeting fixture690, and 3). represent the current positions of tip/tail of the guidetube 50 on the A-P image by a line segment (or other suitable graphicalrepresentation) connecting the X,Z coordinates of the tip to the X,Zcoordinates of the tail (see for example FIGS. 21A-21B), and 4).represent the current positions of tip/tail of the guide tube 50 on thelateral image by a line segment (or other suitable graphicalrepresentation) connecting the Y,Z coordinates of the tip to the Y,Zcoordinates of the tail.

In some embodiments, in constructing the Cartesian coordinate systembased on the two images, it is important to consider directionality.That is, in some embodiments, an x-ray image of the X-Z plane could showpositive X to the right and negative X to the left or vice versa. Insome embodiments, it could show positive Z upward and negative Zdownward or vice versa. In some embodiments, an x-ray image of the Y-Zplane could show positive Y to the right and negative Y to the left orvice versa. In some embodiments, it could show positive Z upward andnegative Z downward or vice versa. In some embodiments, if an incorrectassumption is made about the directionality of one of the axes, it wouldmean that the constructed 3D coordinate system has one or more of itsaxes pointing in the wrong direction. In some embodiments, this may sendthe robot 15 to an incorrect position. In some embodiments, one way ofensuring the correct directionality is to query to the user requestingverification of directionality on the images and/or allowing them toflip (mirror) the images on the display 29. In some embodiments, anotherway of ensuring the correct directionality is to design the targetingfixture 690 so that the radio-opaque markers 730 are spacedasymmetrically. In some other embodiments, another way of ensuring thecorrect directionality is to design the targeting fixture 690 withadditional radio-opaque features that unambiguously identify top,bottom, left, right, front and rear on images. For example, FIGS.22A-22B illustrates expected images on anteroposterior and lateralx-rays of the spine with a well aligned fluoroscopy (x-ray) machine. Asshown, the targeting fixture 690 illustrated in FIGS. 22A-22B includes afeature 755 designed to substantially eliminate ambiguity aboutdirectionality in accordance with one embodiment of the invention. Asshown, the feature 755 could reveal a “L”, “T”, or other symbol on thex-ray when the view is correct so as to substantially eliminatedirectional ambiguity. Furthermore, the “T” feature could be drawn inscript (e.g., ℑ) or other asymmetric letter or symbol used so that if aninverted or mirrored x-ray image is presented, the inverted nature isclear and can be compensated.

In some embodiments, the algorithm described here provides the user withtwo perpendicular x-ray views from which to plan a trajectory, andprovides a visual feedback of the current location of a probe.Typically, these two views might be lateral and anteroposterior (A-P)views. In some embodiments, it might also be desirable for the user tosee a third plane (for example, an axial plane). Based on knowledge ofthe anatomy and landmarks visible on the x-rays, in some embodiments, itis possible to create a rough “cartoon” showing an axial view. In someembodiments, the cartoon may help the user understand the approximatecurrent location of the robot 15 or probe. FIG. 23 shows how such acartoon can be generated from the x-rays. Note that the cartoon will beimperfect with respect to details such as the curvature of the vertebralbody, but key landmarks such as the pedicle boundaries should bereasonably well defined. Such an approach would be based on how atypical vertebra is shaped. For example, FIG. 23 illustrates an axialview of a spine showing how a cartoonish axial approximation of thespine 5601 can be constructed based on a lateral x-ray 5602 and ananteroposterior x-ray 5603 in accordance with one embodiment of theinvention. As shown, locations where key landmarks on the adjacent x-rayviews intersect the cartoon can be identified with horizontal orvertical lines overlapping the cartoon and x-rays. The user positionsthese lines using a software interface or software automaticallyrecognizes these features on the x-rays so that the lines intersect thekey landmarks, such as a line just tangent to the vertebral body leftborder 5604, vertebral body right border 5605, vertebral body anteriorwall 5606, vertebral body posterior wall 5607, posterior spinal canal5608, left inner pedicle border 5609, left outer pedicle border 5610,tip of spinous process 5611, etc. After using the software to move theselines so that they intersect correct locations on the x-rays, thesoftware can then stretch and morph the cartoon as needed to fit theseanatomical limits. A view on the computer display of the axial planeshowing this cartoon and the planned trajectory and current position ofrobot or probe can be generated by the software to provide additionalvisual feedback for the user.

In some embodiments, in order to achieve well aligned x-rays like thoseshown in FIGS. 20A-20B, one possible method is trial and error. Forexample, the user can try to get the x-ray machine aligned to thetargeting fixture 690, attempt to assess alignment by eye, then shoot anx-ray and see how it looks. In some embodiments, if dots are misaligned(for example as shown in FIGS. 19A-19B), adjustments would be made and anew x-ray image can be prepared. This method can be effective but can bedependent on the skill of the operator in assessing alignment and makingcorrections, and therefore can result in x-ray exposure to the patient18 and staff. In some embodiments, it is possible to create a tool toassist in the alignment of the targeting fixture 690. In someembodiments, the tool could be a conventional laser that can be attachedto the emitter or collector panel of the x-ray machine, capable ofpassing a laser beam parallel to the direction that the x-rays willtravel. In some embodiments, the laser could be attached temporarily(using a conventional magnet or adhesive) or permanently, connected toan arm extending from the x-ray machine and oriented in the correctdirection, enabling the directed beam to shine down toward the fixture690. In some embodiments, if the fixture 690 has a geometric,electronic, or other features capable of visual or other feedback to theuser regarding the vector direction of this laser light, it would allowalignment of the x-ray arm without taking any x-rays. An example of sucha feature is shown in FIG. 24A and FIG. 24B. FIGS. 24A-24B illustratesexamples of targeting fixtures 690 that facilitate desired alignment ofthe targeting fixture 690 relative to the x-ray image plane inaccordance with one embodiment of the invention. As shown, someembodiments include a feature 765 temporarily added to the targetingfixture 690 In some embodiments, feature 765 facilitates desiredalignment of the targeting fixture 690 relative to the x-ray image planefrom an AP view when a laser (attached to the face of the x-ray emitteror collector) is directed through the opening 766 and toward thecrosshairs 767 at the base. In some embodiments, if the laser light doesnot strike the crosshairs 767 dead center, further adjustment of thex-ray unit's orientation is needed. The temporarily added feature 765that facilitates desired alignment of the targeting fixture 690 relativeto the x-ray image plane from a lateral view when a laser (attached tothe face of the x-ray emitter or collector) is directed through theopening and toward the crosshairs at the opposite face. In someembodiments, if the laser light does not strike the crosshairs deadcenter, further adjustment of the x-ray unit's orientation is needed.

In some embodiments, this method for aligning the radio-opaque markers730 would have the advantage over trial-and-error methods that areaffected by parallax effects, and as described below, do not confoundthe ability to align markers as needed. For example, with parallax, itmay not be clear to the user when good alignment of the markers 730 isachieved, depending on how symmetrically spaced the markers 730 areabout the center of the image.

With parallax error, the x-rays may not pass through the subject in astraight line and instead travel from emitter to receiver in a conicalpattern. This conical path can produce an image where the details ofanatomy on the 2D x-ray that are closer to the emitter of the x-rayswill appear farther apart laterally than details of the anatomy that arecloser to the receiver plate. In the case of x-ray images in FIGS.20A-20B, instead of the radio-opaque markers 730 appearing overlaid,they may appear as shown in FIGS. 25A-25B. For example, FIGS. 25A-25Billustrates expected images on anteroposterior and lateral x-rays of thespine with a well aligned fluoroscopy (x-ray) machine when parallax ispresent in accordance with one embodiment of the invention. As shown,parallax affects spacing symmetrically about the x,y center of theimage, with locations of markers 730 closer to the receiver plate of thex-ray unit appearing closer to the center of the image.

Further, in the description, two terms used are “near plane” and “farplane”—these terms refer to markers in the 2D views that appear fartherapart or closer together because of parallax. The reason markers arefarther apart or closer together is because of their proximity to theemitter or collector of the x-ray machine, with markers nearer theemitter appearing farther apart and markers nearer the collector closertogether. However, rather than referencing distance from emitter andcollector, “near plane” refers to markers that appear magnified (nearerto the eye) and “far plane” refers to markers that appear more distant.

Parallax will affect the image symmetrically about the center of theimage. For example, in some embodiments, two markers 730 (one in nearplane and one in far plane) that are in the same projected position, andare at the center of the image, may appear to be exactly on top of eachother, whereas markers 730 in the near plane and far plane that are inthe same projected position, but are close to the edge of the image mayappear separated by a substantial distance.

FIG. 26A illustrates two parallel plates with identically positionedradio-opaque markers 730 in accordance with one embodiment of theinvention. As shown, this illustrates possible marker 730 separation onan x-ray from markers 730 on two plates that are in the same projectedline of sight. FIG. 26B illustrates resulting expected x-raydemonstrating how marker overlay is affected due to parallax using thetwo parallel plates as shown in FIG. 26A in accordance with oneembodiment of the invention. By comparing the two parallel plates withidentically positioned radio-opaque markers 730 shown in FIG. 26A, withthe resulting expected x-ray in FIG. 26B demonstrates how marker overlayis affected due to parallax. In some embodiments, an algorithm can beimplemented to account for this parallax effect. By doing so, thegraphical image indicating the position of the probe or robot 15 can beadjusted to more accurately account for the perceived shift caused byparallax.

In some embodiments, the algorithm requires information to be gatheredon the near and far plane positions of the markers 730 on the image.That is, the user can indicate, using software or an automatic scan ofthe image, the spacing between markers 730, as shown in FIG. 27, whichshows a representation of the rendering of a computer screen with anx-ray image that is affected by parallax overlaid by graphical markers732, 734 over the radio-opaque markers 730 on two plates that have thesame geometry in accordance with one embodiment of the invention. Insome embodiments, the spacing between near plane and far plane markers730 is known because of earlier calibration of the plates 700 in whichthe markers 730 are embedded, and the horizontal and vertical positionsof the markers 730 are detectable relative to the center of the image.Therefore, in some embodiments, the parallax shift of the markers 730can be calculated and applied to the mapping of any calculated threedimensional points on to the two dimensional image, and application ofany necessary positional shift. For example, in some embodiments, itmight be of interest to display a line segment on the two dimensionalimage representing how the shaft of a probe or robot 15 guide tube 50(that is being tracked using optical tracking) would appear followingx-ray imaging. In some embodiments, the x-axis, y-axis, and z-axislocation of each end of the line segment (which has been calculated fromoptical tracking data) can be shifted based on the known parallax.Further, in some embodiments, a new line segment can be displayed thatbetter represents how this projected object should appear on the 2Dx-ray image.

In some embodiments, a method of implementing this system of twoorthogonal fluoroscopy images to control a robot 15 can involvecombining a robot 15 and fluoroscopy unit into a single interconnecteddevice. There could be some advantages of this combination. For example,a conventional rotating turntable mechanism could be incorporated thatcould swing the fluoro arm into place, while at the same time swingingthe robot arm 23 out of place (since the robot 15 would typically not bein the surgical field 17 at the same time as the fluoro arm).Furthermore, in some embodiments, the size of the robot arm 23 could bereduced compared to the stand-alone robot 15 because the fluoro arm'smass would serve as a counter-balance weight to help stabilize the robotarm 23. Moreover, in some embodiments, with integration, the fluoroscopyunit can more quickly transfer the image to the computer 100 and overlaywith a graphical plot, for instance, as line segments starting at thecenter of the image and extending radially (similar to pie slices)around the image to facilitate appropriate marker 730 overlay. In someembodiments, overlaid near and far plane markers 730 should always fallon the same ray if the plates 690 with embedded markers 730 on thesubject are aligned substantially parallel (see for example FIG. 28which shows a graphical overlay for the x-ray image screen intended tohelp the user physically line up the x-ray machine). In someembodiments, the graphical overlay for the x-ray image screen can helpthe user physically line up the x-ray machine to avoid parallax. Withparallax, any pair of corresponding markers on the 2 plates should lieon the same radial line, although the one in the far plane will liecloser to the middle of the image. In some embodiments, this overlaycould be a physical object such as transparent film, or acomputer-generated graphical image. In some embodiments, lines arespaced radially by 10 degrees, but actual spacing (frequency of lines)and regions in which lines are drawn could be user selectable.

Some embodiments can include mapping a 3D anatomical coordinate systemon to two 2D orthogonal views (and vice versa) while consideringparallax. For example, in some embodiments, a rigid frame is mounted tothe patient and two perpendicular x-rays are taken to create a 3Dcoordinate system. To define this 3D coordinate system, a method isneeded to map points from the 2D views (each with parallax) to the 3Dvolume and vice versa. The 3D coordinate system has coordinates x, y, zwhile the two 2D coordinate systems have coordinates X_(AP),Z_(AP) andx_(Lat),z_(Lat) (“AP” for “anteroposterior” and “Lat” for “lateral”views).

In some embodiments, it can be assumed that the x-ray path from emitterto receiver is conical, and therefore linear interpolation/extrapolationcan be used to adjust the positions of represented points. In someembodiments, software can calculate the distance of each landmark fromthe center of the image (indicated by dashed or dotted arrows). Thesedistances, together with the known distance between near plane and farplane plates, can provide the necessary information to account for theparallax shift when mapping graphical objects whose positions are knownin 3D back on to this 2D image.

Some embodiments can include solving to map x, y, z onto X_(AP),Z_(AP)and X_(Lat),Z_(Lat). For example, consider two intermediate 2D AP andlateral views represented as follows:

x _(ta)=(x−x _(oa))s _(AP)

z _(ta)=(z−z _(oa))s _(AP)

y _(tl)=(y−y _(ol))s _(Lat)

z _(tl)=(z−z _(ol))s _(Lat)

Where x_(ta) and z_(ta) can be called temporary scaled values of x and zin the AP plane, y_(tl) and z_(tl) are temporary scaled values of y andz in the Lat plane, s_(AP) is the scaling factor in the AP plane,determined from the known near plane¹ marker spacing. s_(Lat) is thescaling factor in the Lat plane, determined from the known near planemarker spacing of the lateral markers, and x_(oa), z_(oa), y_(ol), andz_(ol) are offsets in AP and Lat planes that position the markers suchthat they are as they appear centered about the image determined fromregistered positions of the markers on the images. In other words,(x_(ta), z_(ta))=(0,0) represents the center of the AP image and(y_(tl), z_(tl))=(0,0) represents the center of the lateral image. Theseplanar values would be enough to display a 2D representation if noparallax were present or near plane markers were only being displayed.

In some embodiments, to find x_(oa), z_(oa), y_(ol), and z_(ol) considerpairs of points on the x-rays, because the ratio of distance from centeron the x-ray is the same as the ratio of distance from center on thetemporary scaled values. For example:

$\frac{x_{AP1}}{x_{AP2}} = {\frac{x_{ta1}}{x_{ta2}} = \frac{\left( {x_{1} - x_{oa}} \right)s_{AP}}{\left( {x_{2} - x_{oa}} \right)s_{AP}}}$${\left( \frac{x_{AP1}}{x_{AP2}} \right)\left( {x_{2} - x_{oa}} \right)} = {x_{1} - x_{oa}}$${{x_{2}\left( \frac{x_{AP1}}{x_{AP2}} \right)} - x_{1}} = {{x_{oa}\left( \frac{x_{AP1}}{x_{AP2}} \right)} - x_{oa}}$${x_{oa}\left( {\frac{x_{AP1}}{x_{AP2}} - 1} \right)} = {{x_{2}\left( \frac{x_{AP1}}{x_{AP2}} \right)} - x_{1}}$$x_{oa} = \frac{{x_{2}\left( \frac{x_{AP1}}{x_{AP2}} \right)} - x_{1}}{\frac{x_{AP1}}{x_{AP2}} - 1}$

In some embodiments, it can be seen from this equation that it isimportant to stay away from points where x_(AP1)≈x_(AP2) because itwould result in a divide by zero error. Similar equations can be writtenfor z_(oa), y_(ol), and z_(ol) as follows:

$z_{oa} = \frac{{z_{2}\left( \frac{z_{AP1}}{z_{AP2}} \right)} - z_{1}}{\frac{z_{AP1}}{z_{AP2}} - 1}$$y_{ol}\frac{{y_{2}\left( \frac{y_{Lat1}}{y_{Lat2}} \right)} - y_{1}}{\frac{y_{Lat1}}{y_{Lat2}} - 1}$$z_{ol} = \frac{{z_{2}\left( \frac{z_{Lat1}}{z_{Lat2}} \right)} - z_{1}}{\frac{z_{Lat1}}{z_{Lat2}} - 1}$

This mapping to temporary scaled values gets the near plane markersmapped correctly, but adjustment is needed to account for any positionother than near plane as follows:

x _(AP) =x _(ta) k _(a)(y)

z _(AP) =z _(ta) k _(a)(y)

y _(Lat) =y _(tl) k _(l)(x)

z _(Lat) =z _(tl) k _(l)(x)

As specified, k_(a) is a function of y and k_(l) is a function of x. Fork_(a), this function is a linear interpolation function, in which if yis they position of the near plane (y_(n)), then k_(a)=1 and if y is they position of the far plane (y_(f)), then k_(a) is the ratio of farplane spacing to near plane spacing, r_(a). For k_(l), this function isa linear interpolation function, in which if x is the x position of thenear plane (x_(n)), then k_(l)=1 and if x is the x position of the farplane (x_(f)), then k_(l) is the ratio of far plane spacing to nearplane spacing, r_(l). Note that y_(n), y_(f), x_(n), and x_(f) are in acoordinate system with the origin at the center of the image.

${{k_{a} = {1 - {\left( \frac{y_{tl} - y_{n}}{y_{f} - y_{n}} \right)\left( {1 - r_{a}} \right)}}}k_{l}} = {1 - {\left( \frac{x_{ta} - x_{n}}{x_{f} - x_{n}} \right)\left( {1 - r_{l}} \right)}}$

Combining equations,

$x_{AP} = {x_{ta}\left\lbrack {1 - {\left( \frac{y_{tl} - y_{n}}{y_{f} - y_{n}} \right)\left( {1 - r_{a}} \right)}} \right\rbrack}$$z_{AP} = {z_{ta}\left\lbrack {1 - {\left( \frac{y_{tl} - y_{n}}{y_{f} - y_{n}} \right)\left( {1 - r_{a}} \right)}} \right\rbrack}$$y_{Lat} = {y_{tl}\left\lbrack {1 - {\left( \frac{x_{ta} - x_{n}}{x_{f} - x_{n}} \right)\left( {1 - r_{l}} \right)}} \right\rbrack}$$z_{Lat} = {z_{tl}\left\lbrack {1 - {\left( \frac{x_{ta} - x_{n}}{x_{f} - x_{n}} \right)\left( {1 - r_{l}} \right)}} \right\rbrack}$

It should also be possible to map x_(AP), z_(AP), y_(Lat), and z_(Lat)onto x, y, z. Having 4 equations and 4 unknowns:

$x_{AP} = {x_{ta}\left\lbrack {1 - {\left( \frac{y_{tl} - y_{n}}{y_{f} - y_{n}} \right)\left( {1 - r_{a}} \right)}} \right\rbrack}$${1 - \frac{x_{AP}}{x_{ta}}} = {\left( \frac{y_{tl} - y_{n}}{y_{f} - y_{n}} \right)\left( {1 - r_{a}} \right)}$${\left( {1 - \frac{x_{AP}}{x_{ta}}} \right)\left( \frac{y_{f} - y_{n}}{1 - r_{a}} \right)} = {y_{tl} - y_{n}}$$y_{tl} = {{\left( {1 - \frac{x_{AP}}{x_{ta}}} \right)\left( \frac{y_{f} - y_{n}}{1 - r_{a}} \right)} + y_{n}}$

Then substitute into this equation:

$y_{Lat} = {y_{tl}\left\lbrack {1 - {\left( \frac{x_{ta} - x_{n}}{x_{f} - x_{n}} \right)\left( {1 - r_{l}} \right)}} \right\rbrack}$$y_{Lat} = {\left\lbrack {{\left( {1 - \frac{x_{AP}}{x_{ta}}} \right)\left( \frac{y_{f} - y_{n}}{1 - r_{a}} \right)} + y_{n}} \right\rbrack\left\lbrack {1 - {\left( \frac{x_{ta} - x_{n}}{x_{f} - x_{n}} \right)\left( {1 - r_{l}} \right)}} \right\rbrack}$

And solve for x_(ta):

$\mspace{20mu}{y_{Lat} = {\left\lbrack {\left( \frac{y_{f} - y_{n}}{1 - r_{a}} \right) - {\frac{x_{AP}}{x_{ta}}\left( \frac{y_{f} - y_{n}}{1 - r_{a}} \right)} + y_{n}} \right\rbrack\left\lbrack {1 - {\left( \frac{1 - r_{l}}{x_{f} - x_{n}} \right)\left( {x_{ta} - x_{n}} \right)}} \right\rbrack}}$$y_{Lat} = {\left\lbrack {\left\lbrack {\left( \frac{y_{f} - y_{n}}{1 - r_{a}} \right) + y_{n}} \right\rbrack - \left\lbrack {\frac{x_{AP}}{x_{ta}}\left( \frac{y_{f} - y_{n}}{1 - r_{a}} \right)} \right\rbrack} \right\rbrack\left\lbrack {{\left\lbrack {1 + {x_{n}\left( \frac{1 - r_{l}}{x_{f} - x_{n}} \right)}} \right\rbrack - {\left. \quad\left\lbrack {x_{ta}\left( \frac{1 - r_{l}}{x_{f} - x_{n}} \right)} \right\rbrack \right\rbrack\mspace{20mu} y_{Lat}}} = {{{\left\lbrack {A - \frac{B}{x_{ta}}} \right\rbrack\left\lbrack {C - {Dx_{ta}}} \right\rbrack}\mspace{20mu} y_{Lat}} = {{{AC} - \frac{BC}{x_{ta}} - {ADx_{ta}} + {{BD}\mspace{20mu} A\; C} + {BD} - y_{Lat}} = {{\frac{BC}{x_{ta}} + {AD{x_{ta}\mspace{20mu}({AD})}x_{ta}^{2}} + {\left( {y_{Lat} - {AC} - {BD}} \right)x_{ta}} + \left( {BC} \right)} = 0}}}} \right.}$

Quadratic formula:

$x = \frac{{- b} \pm \sqrt{b^{2} - {4ac}}}{2a}$$x_{ta} = \frac{{- \left( {y_{Lat} - {AC} - {BD}} \right)} \pm \sqrt{\left( {y_{Lat} - {AC} - {BD}} \right)^{2} - {4\left( {AD} \right)\left( {BC} \right)}}}{2\left( {AD} \right)}$

Where:

$A = {\left( \frac{y_{f} - y_{n}}{1 - r_{a}} \right) + y_{n}}$$B = {x_{AP}\left( \frac{y_{f} - y_{n}}{1 - r_{a}} \right)}$$C = {1 + {\left( \frac{1 - r_{l}}{x_{f} - x_{n}} \right)x_{n}}}$$D = \frac{1 - r_{l}}{x_{f} - x_{n}}$

Then plug into this equation to solve for y_(tl):

$y_{tl} = {{\left( {1 - \frac{x_{AP}}{x_{ta}}} \right)\left( \frac{y_{f} - y_{n}}{1 - r_{a}} \right)} + y_{n}}$

Then plug into this equation to solve for z_(tl):

$Z_{tl} = {z_{Lat}/\left\lbrack {1 - {\left( \frac{x_{ta} - x_{n}}{x_{f} - x_{n}} \right)\left( {1 - r_{l}} \right)}} \right\rbrack}$

Then plug into this equation to solve for z_(ta):

$z_{ta} = {z_{AP}/\left\lbrack {1 - {\left( \frac{y_{tl} - y_{n}}{y_{f} - y_{n}} \right)\left( {1 - r_{a}} \right)}} \right\rbrack}$

Solve differently to give another option for z:

$y_{Lat} = {y_{tl}\left\lbrack {1 - {\left( \frac{x_{ta} - x_{n}}{x_{f} - x_{n}} \right)\left( {1 - r_{l}} \right)}} \right\rbrack}$${\left( \frac{x_{ta} - x_{n}}{x_{f} - x_{n}} \right)\left( {1 - r_{l}} \right)} = {1 - \frac{y_{Lat}}{y_{rl}}}$${\left( {x_{ta} - x_{n}} \right)\left( \frac{1 - r_{l}}{x_{f} - x_{n}} \right)} = {1 - \frac{y_{Lat}}{y_{rl}}}$${{x_{ta}\left( \frac{1 - r_{l}}{x_{f} - x_{n}} \right)} - {x_{n}\left( \frac{1 - r_{l}}{x_{f} - x_{n}} \right)}} = {1 - \frac{y_{Lat}}{y_{rl}}}$${x_{ta}\left( \frac{1 - r_{l}}{x_{f} - x_{n}} \right)} = {1 - \frac{y_{Lat}}{y_{rl}} + {x_{n}\left( \frac{1 - r_{l}}{x_{f} - x_{n}} \right)}}$$x_{ta} = {{\left( {1 - \frac{y_{Lat}}{y_{rl}}} \right)\left( \frac{x_{f} - x_{n}}{1 - r_{l}} \right)} + x_{n}}$

Substitute into:

$x_{AP} = {x_{ta}\left\lbrack {1 - {\left( \frac{y_{tl} - y_{n}}{y_{f} - y_{n}} \right)\left( {1 - r_{a}} \right)}} \right\rbrack}$$x_{AP} = {\left\lbrack {{\left( {1 - \frac{y_{Lat}}{y_{rl}}} \right)\left( \frac{x_{f} - x_{n}}{1 - r_{l}} \right)} + x_{n}} \right\rbrack\left\lbrack {1 - {\left( \frac{y_{tl} - y_{n}}{y_{f} - y_{n}} \right)\left( {1 - r_{a}} \right)}} \right\rbrack}$

And solve for y_(tl):

$\mspace{20mu}{x_{AP} = {\left\lbrack {\left( \frac{x_{f} - x_{n}}{1 - r_{l}} \right) - {\frac{y_{Lat}}{y_{r\iota}}\left( \frac{x_{f} - x_{n}}{1 - r_{l}} \right)} + x_{n}} \right\rbrack\left\lbrack {1 - {\left( {y_{tl} - y_{n}} \right)\left( \frac{1 - r_{a}}{y_{f} - y_{n}} \right)}} \right\rbrack}}$$x_{AP} = {\left\lbrack {\left\lbrack {\left( \frac{x_{f} - x_{n}}{1 - r_{l}} \right) + x_{n}} \right\rbrack - \left\lbrack {\frac{y_{Lat}}{y_{r\iota}}\left( \frac{x_{f} - x_{n}}{1 - r_{l}} \right)} \right\rbrack} \right\rbrack\left\lbrack {{\left\lbrack {1 + {y_{n}\left( \frac{1 - r_{a}}{y_{f} - y_{n}} \right)}} \right\rbrack - {\left. \quad\left\lbrack {y_{tl}\left( \frac{1 - r_{a}}{y_{f} - y_{n}} \right)} \right\rbrack \right\rbrack\mspace{20mu} x_{AP}}} = {{{\left\lbrack {A - \frac{B}{y_{tl}}} \right\rbrack\ \left\lbrack {C - {Dy_{tl}}} \right\rbrack}\mspace{20mu} x_{AP}} = {{{AC} - \frac{BC}{y_{tl}} - {ADy_{tl}} + {{BD}\mspace{20mu} A\; C} + {BD} - x_{AP}} = {{\frac{BC}{y_{tl}} + {AD{y_{tl}\mspace{20mu}({AD})}y_{tl}^{2}} + {\left( {x_{AP} - {AC} - {BD}} \right)y_{tl}} + \left( {BC} \right)} = 0}}}} \right.}$

Quadratic formula:

$x = \frac{{- b} \pm \sqrt{b^{2} - {4ac}}}{2a}$$y_{tl} = \frac{{- \left( {x_{AP} - {AC} - {BD}} \right)} \pm \sqrt{\left( {x_{AP} - {AC} - {BD}} \right)^{2} - {4\left( {AD} \right)\left( {BC} \right)}}}{2\left( {AD} \right)}$

Where:

${A = {\left( \frac{x_{f} - x_{n}}{1 - r_{l}} \right) + x_{n}}}{B = {y_{Lat}\left( \frac{x_{f} - x_{n}}{1 - r_{l}} \right)}}{C = {1 + {y_{n}\left( \frac{1 - r_{a}}{y_{f} - y_{n}} \right)}}}$$D = \frac{1 - r_{a}}{y_{f} - y_{n}}$

From these equations, it is possible to go from a known x, y, zcoordinate to the perceived x_(AP),z_(AP) and x_(Lat),z_(Lat)coordinates on the two views, or to go from known x_(AP),z_(AP) andx_(Lat),z_(Lat) coordinates on the two views to an x, y, z coordinate inthe 3D coordinate system. It is therefore possible to plan a trajectoryon the x_(AP),z_(AP) and x_(Lat),z_(Lat) views and determine what thetip and tail of this trajectory are, and it is also possible to displayon the x_(AP),z_(AP) and x_(Lat),z_(Lat) views the current location ofthe robot's end effectuator.

In some embodiments, additional measurement hardware (for example,conventional ultrasound, laser, optical tracking, or a physicalextension like a tape measure) can be attached to the fluoro unit tomeasure distance to the attached plates, or other points on the anatomyto ensure that plates are parallel when fluoro images are obtained.

In some embodiments, the identity of the surgical instrument 35 can beused by the control system for the computing device or other controllerfor the surgical robot system 1. In some embodiments, the control systemcan automatically adjust axial insertion and/or forces and appliedtorques depending upon the identity of the surgical instrument 35.

In some embodiments, when performing a typical procedure for needle7405, 7410 or probe insertion (for biopsy, facet injection, tumorablation, deep brain stimulation, etc.) a targeting fixture 690 is firstattached by the surgeon or technician to the patient 18. The targetingfixture 690 is either clamped to bone (open or percutaneously), adheredas a rigid object to the skin, or unrolled and adhered to the skin. Insome embodiments, the roll 705 could have a disposable drapeincorporated. If a flexible roll 705 is used, reflective markers 720will then be snapped into place in some embodiments.

In some embodiments, once a targeting fixture 690 is attached, thepatient 18 can receive an intraoperative 3D image (Iso-C, O-Arm, orintraoperative CT) with radio-opaque markers 730 included in the fieldof view along with the region of interest. In some embodiments, for bestaccuracy and resolution, a fine-slice image is preferred (CT slicespacing=1 mm or less). The 3D scan has to include the radio-opaquemarkers 730 and the anatomy of interest; not including both woulddisallow calibration to the robot 15.

In some embodiments, the 3D image series is transferred to (or acquireddirectly to) the computer 100 of the robot 15. The 3D image has to becalibrated to the robot's position in space using the locations on the3D image of the radio-opaque markers 730 that are embedded in thetargeting fixture 690. In some embodiments, this calibration can be doneby the technician scrolling through image slices and marking them usingthe software, or by an algorithm that automatically checks each slice ofthe medical image, finds the markers 730, verifying that they are themarkers 730 of interest based on their physical spacing (the algorithmis documented herein). In some embodiments, to ensure accuracy, limitsubjectivity, and to speed up the process, image thresholding is used tohelp define the edges of the radio-opaque marker 730, and then to findthe center of the marker 730 (the program is documented herein). Someembodiments of the software can do the necessary spatial transformationsto determine the location in the room of the robot's markers relative toanatomy through standard rigid body calculations. For example, byknowing the locations of the radio-opaque markers 730 in the coordinatesystem of the medical image, and knowing the locations of the activemarkers 720 on the calibration frame 700 relative to these radio-opaquemarkers 730, and monitoring the locations of the active markers on therobot 15 and targeting fixture 690.

Some embodiments allow the surgeon to use the software to plan thetrajectories for needles/probes 7405, 7410. In some embodiments, thesoftware will allow any number of trajectories to be stored for useduring the procedure, with each trajectory accompanied by a descriptor.

In some embodiments, the robot 15 is moved next to the procedure tableand cameras 8200 for tracking robot 15 and patient 18 are activated. Thecameras 8200 and robot 15 are positioned wherever is convenient for thesurgeon to access the site of interest. The marker mounts on the robot15 have adjustable positions to allow the markers 720 to face toward thecameras 8200 in each possible configuration. In some embodiments, ascreen can be accessed to show where the robot 15 is located for thecurrent Z-frame 72 position, relative to all the trajectories that areplanned. In some embodiments, the use of this screen can confirm thatthe trajectories planned are within the range of the robot's reach. Insome embodiments, repositioning of the robot 15 is performed at thistime to a location that is within range of all trajectories. Alternatelyor additionally, in some embodiments, the surgeon can adjust the Z-frame72 position, which will affect the range of trajectories that the robot15 is capable of reaching (converging trajectories require less x-yreach the lower the robot 15 is in the z-axis 70). During this time,substantially simultaneously, a screen shows whether markers 720, 730 onthe patient 18 and robot 15 are in view of the cameras 8200.Repositioning of the cameras 8200, if necessary, is also performed atthis time for good visibility.

In some embodiments, the surgeon then selects the first plannedtrajectory and he/she (or assistant) presses “go”. The robot 15 moves inthe x-y (horizontal) plane and angulates roll 62 and pitch 60 until theend-effectuator 30 tube intersects the trajectory vector. In someembodiments, during the process of driving to this location, a smalllaser light will indicate end-effectuator 30 position by projecting abeam down the trajectory vector toward the patient 18. This laser simplysnaps into the top of the end-effectuator 30 tube. In some embodiments,when the robot's end-effectuator 30 tube coincides with the trajectoryvector to within the specified tolerance, auditory feedback is providedto indicate that the desired trajectory has been achieved and is beingheld. Alternately or additionally, in some embodiments, light of ameaningful color is projected on the surgical field 17. For example, insome embodiments, movement of the patient 18 or robot 15 is detected byoptical markers 720 and the necessary x-axis 66, y-axis 68, roll 62, andpitch 60 axes are adjusted to maintain alignment.

In some embodiments, the surgeon then drives Z-frame 72 down until thetip of the end-effectuator 30 reaches the desired distance from theprobe's or needle's target (typically the skin surface). While moving,the projected laser beam point should remain at a fixed location sincemovement is occurring along the trajectory vector. Once at the desiredZ-frame 72 location, in some embodiments, the surgeon or other user canselect an option to lock the Z-tube 50 position to remain at the fixeddistance from the skin during breathing or other movement. At thispoint, the surgeon is ready to insert the probe or needle 7405, 7410. Ifthe length of the guide tube 50 has been specified and a stop on theneedle 7405, 7410 or probe is present to limit the guide tube 50 aftersome length has been passed, the ultimate location of the tip of theprobe/needle 7405, 7410 can be calculated and displayed on the medicalimage in some embodiments. As described earlier, Additionally, in someembodiments, it is possible to incorporate a mechanism at the entry ofthe guide tube 50 that is comprised of a spring-loaded plunger 54 with athrough-hole, and measures electronically the depth of depression of theplunger 54, corresponding to the amount by which the probe or needle7405, 7410 currently protrudes from the tip of the guide tube 50.

In some embodiments, at any time during the procedure, if there is anemergency and the robot 15 is in the way of the surgeon, the “E-stop”button can be pressed on the robot 15, at which point all axes exceptthe Z-frame axis 72 become free-floating and the robot's end-effectuator30 can be manually removed from the field by pushing against theend-effectuator 30.

Some embodiments can include a bone screw or hardware procedure. Forexample, during a typical procedure for conventional screw or hardwareinsertion in the spine, the patient 18 is positioned prone (or otherposition) on the procedure table, and is supported. In some embodiments,a targeting fixture 690 is attached to the patient's spine by thesurgeon or technician. In some embodiments, the targeting fixture 690 iseither clamped to bone (open or percutaneously) or unrolled and adheredto the skin (for example using roll 705). The roll 705 could have adisposable drape incorporated. If a flexible roll 705 is used,reflective markers 720 will then be snapped into place in someembodiments.

In some embodiments, once a targeting fixture 690 is attached, thepatient 18 can undergo an intraoperative 3D image (Iso-C, O-Arm, orintraoperative CT) with radio-opaque markers 730 included in the fieldof view along with the bony region of interest. In some embodiments, forbest accuracy and resolution, a fine-slice image is preferred (where theCT slice spacing=1 mm or less). The 3D scan in some embodiments has toinclude the radio-opaque markers 730 and the bony anatomy; not includingboth would disallow calibration to the robot 15.

In some embodiments, the 3D image series is transferred to (or acquireddirectly to) the computer 100 of the robot 15, and the 3D image iscalibrated in the same way as described above for needle 7405, 7410 orprobe insertion. The surgeon then uses the software to plan thetrajectories for hardware instrumentation (e.g., pedicle screw, facetscrew). Some embodiments of the software will allow any number oftrajectories to be stored for use during the procedure, with eachtrajectory accompanied by a descriptor that may just be the level andside of the spine where screw insertion is planned.

In some embodiments, the robot 15 is moved next to the table and cameras8200 for tracking robot 15 and patient 18 are activated. The cameras8200 are positioned near the patient's head. In some embodiments, themarkers for the robot 15 are facing toward the cameras 8200, typicallyin the positive y-axis 68 direction of the robot's coordinate system. Insome embodiments, a screen can be accessed to show where the robot 15 islocated relative to all the trajectories that are planned for thecurrent Z-frame 72 position. Using this screen it can be confirmed thatthe trajectories planned are within the range of the robot's reach. Insome embodiments, repositioning of the robot 15 to a location that iswithin range of all trajectories is performed at this time. Alternatelyor additionally, in some embodiments, the surgeon can adjust the Z-frame72 position, which will affect the range of trajectories that the robot15 is capable of reaching (converging trajectories require less x-yreach the lower the robot 15 is in Z). During this time, simultaneouslyin some embodiments, a screen shows whether markers 720 on the patient18 and robot 15 are in view of the cameras 8200. Repositioning of thecameras 8200, if necessary, is also performed at this time for goodvisibility.

In some embodiments, the surgeon then selects the first plannedtrajectory and he/she (or assistant) presses “go”. The robot 15 moves inthe x-y (horizontal) plane and angulates roll 62 and pitch 60 until theend-effectuator 30 tube intersects the trajectory vector. During theprocess of driving to this location, in some embodiments, a small laserlight will indicate end-effectuator 30 position by projecting a beamdown the trajectory vector toward the patient 18. This laser simplysnaps into the top of the end-effectuator guide tube 50. When therobot's end-effectuator guide tube 50 coincides with the trajectoryvector to within the specified tolerance, auditory feedback is providedin some embodiments to indicate that the desired trajectory has beenachieved and is being held. In some embodiments, movement of the patient18 or robot 15 is detected by optical markers 720 and the necessaryx-axis 66, y-axis 68, roll 62, and pitch 60 axes are adjusted tomaintain alignment.

In some embodiments of the invention, the surgeon then drives Z-frame 72down until the tip of the end-effectuator 30 reaches a reasonablestarting distance from the site of operation, typically just proximal tothe skin surface or the first tissues encountered within the surgicalfield 17. While moving, the projected laser beam point should remain ata fixed location since movement is occurring along the trajectoryvector. Once at the desired location, the user may or may not select anoption to lock the Z-tube 50 position to remain at the fixed distancefrom the anatomy during breathing or other movement.

One problem with inserting conventional guide-wires and screws into bonethrough any amount of soft tissue is that the screw or wire maysometimes deflect, wander, or “skive” off of the bone in a trajectorythat is not desired if it does not meet the bone with a trajectoryorthogonal to the bone surface. To overcome this difficulty, someembodiments can use a specially designed and coated screw specificallyintended for percutaneous insertion. Some other embodiments can use anend-effectuator 30 tip fitted with a guide tube 50 or dilator, capableof being driven all the way down to the bone. In this instance, theguide tube 50 needs to have a sharp (beveled) leading edge 30 b, and mayneed teeth or another feature to secure it well to the bone once incontact. This beveled tube 50 (i.e. guide tube 50 that includes beveledleading edge 30 b) is driven through soft tissue and next to bonethrough one of two different methods using the surgical robot system 1as described.

In applications where conventional screws are to be driven into bone,the surgeon may want to move the end-effectuator tip 30, fitted with aguide tube 50 or a conventional dilator, all the way down to the bone.Referring to FIG. 29 showing steps 6210, 6215, 6220, 6225, 6230, 6235,6240, 6245, and either 6250, 6255, 6260, and 6260, or 6270, 6275, 6280and 6285, two embodiments address this need. In some embodiments, theuser can insert the tube 50 and force it down the axis Z-tube axis 64 byhand, or with the robot 15 until a peak in force is registered bytactile feel or by a conventional force sensor on the end-effectuator 30(signaling contact with bone). At this point, it is no longer necessaryfor the tip of the drill bit 42 to be positioned past the tip of thetube 50 (in fact be better to have it slightly retracted). As describedearlier, a drill bit 42 can include a drill stop, and the drill bit 42can be locked and held. In some embodiments, the stop on the drill bit42 can then be adjusted by pulling one of the releases and slightlyadjusting its position. Then, the tube 50 can be brought up against boneand locked there. Now, the stop can be adjusted to show how much thedrill bit 42 would protrude beyond the tip. This same value can be usedto offset (extrapolate) the tip of the tube 50 on the software, showingthe user where the tip of the drill bit 42 will end up.

In some embodiments, the Z-tube axis 64 is fitted with a conventionalforce sensor with continuous force readings being displayed on thescreen (such as display means 29). In some embodiments, the Z-frame 72is then driven down into tissue while continuously adjusting the x-axis66 and y-axis 68 to keep the tube 50 aligned with the trajectory vector.In some embodiments, the steps of 6210, 6215, 6220, 6225, 6230, 6235,6240, 6245, 6250 and 6255 can be used to drive the tube 50 toward thetarget. In this instance, roll 62 and pitch 60, defining orientation,should not change while moving x-axis 66, y-axis 68, and the Z-frame 72as Z-axis 70 along this vector, while holding Z-tube 50 rigidly lockedat mid-range. For this procedure, in some embodiments, the Z-tube 50stiffness must be set very high, and may require a conventionalmechanical lock to be implemented. In some embodiments, if Z-tube 50 isnot stiff enough, a counter force from the tissues being penetrated maycause it to move back in the opposite direction of Z-frame 72, and thetube 50 will not have any net advancement. In some embodiments, based onthe surgeon's previous experience and lab testing, Z-frame 72 is drivendown until a force level from the monitored force on Z-tube 50 matchesthe force typical for collision with bone (step 6260).

At this point, in some embodiments, the guide tube 50 is adjacent tobone and the surgeon may wish to drill into the bone with a conventionalguide-wire or drill bit, or insert a screw. For screw prep andinsertion, in some embodiments, the surgeon either uses a method thatincorporates guide-wires, or a method that does not use guide-wires.

Some embodiments include a guide-wire method. For example, in someembodiments, a guide-wire is drilled into bone through the guide tube50. After the guide-wire is in place, Z-frame 72 and tube 50 are drivenupward along the trajectory vector until outside the body. In someembodiments, the tube is then released with a quick release from therobot's end-effectuator 30 so it can be positioned at the nexttrajectory. In some embodiments, a cannulated screw, already commonlyused in spine surgery, can then be driven in place over the guide-wire.

Some embodiments include a non-guide-wire method. For example, a pilothole may or may not be drilled first. In some embodiments, a screw isthen driven into bone directly through the guide tube 50, which abutsbone. In some embodiments, the tip of the screw may have the specialnon-skiving design mentioned above.

In some embodiments, if hardware other than a screw is being inserted,the surgeon may wish to dilate soft tissue. In some embodiments, adilated path would enable larger and/or more tools and implants to beinserted. In some embodiments, dilation is performed by sliding a seriesof larger and larger diameter tubes over the initial central shaft ortube. In some embodiments, a series of dilators, specially designed tointegrate to the robot's end-effectuator 30, sequentially snap on toeach other for this purpose.

In some embodiments, after the screw or hardware has been inserted inthe first trajectory, the surgeon drives the robot 15 back up thetrajectory vector away from the patient 18. In some embodiments, afterthe end-effectuator 30 is clear of the patient 18 in the Z direction,the next trajectory is selected and the robot 15 repeats the abovesteps.

In some embodiments, at any time during the procedure, if there is anemergency and the robot 15 is in the way of the surgeon, the “E-stop”button can be pressed on the robot 15, at which point all axes exceptZ-frame 72 become free-floating, and the robot's end-effectuator 30 canbe manually removed from the field by pushing against theend-effectuator.

In some embodiments, for nerve avoidance during medical procedures, aspecial conventional dilator tube (not shown) that can be used with therobot 15. In some embodiments, the dilator tube can include multipleelectrodes at its tip that can be sequentially activated to find notonly whether a nerve is nearby, but also to find which radial directionis the nearest direction toward the nerve. Some embodiments incorporatethis guide tube 50 and can identify, warn or incorporate automaticalgorithms to steer clear of the nerve.

In some embodiments, it is known that pairs of bone screws such aspedicle screws have better resistance to screw pullout if they areoriented so that they converge toward each other. In some embodiments,for the best potential biomechanical stability, a two-screw surgicalconstruct can consist of specially designed conventional screws thatwould interconnect in the X Z plane (not shown). That is, one screw canhave a socket to accept a threaded portion of the other screw so thatthe screws interconnect at their tips. A procedure such as this requiresexceptional accuracy, otherwise the screw tips would not properlyintersect, and is therefore especially well-suited for a surgical robot15. This type of hardware is useful with certain embodiments of theinvention.

In some embodiments, instead of only straight lines, the surgeon hasseveral options for trajectory planning—straight, curved or boundary forsafe-zone surgery. For curved pathway planning, in some embodiments, thesurgeon can draw a path on the medical image that has curvature of auser-selectable radius. In some embodiments, special conventionalneedles and housings can be used to execute these curved paths. In safezone surgery (tumor or trauma), in some embodiments, the surgeon firstplans a box or sphere around the region on the medical image withinwhich the probe tip, incorporating a drill or ablation instrument, willbe allowed to reside. In some embodiments, the robot 15 is driven downalong a trajectory vector either automatically or manually as describedabove to position the tip of the probe to be in the center of the safezone. In some embodiments, the surgeon would then be able pick thetool's axis of rotation (orthogonal to the long axis) based on thedesired impact he/she would like for the purpose of preserving tissueand maximizing efficiency and effectiveness for the task at hand. Forexample, in some embodiments, an axis of rotation at the surface of theskin could be selected to minimize the amount by which the tool travelslaterally and rips the skin.

In some embodiments, the robot 15 uses optical markers for tracking.Some embodiments are able to provide accurate localization of the robot15 relative to the patient 18, and utilize the LPS because of theadvantage of not being limited to line-of-sight. Additionally, in someembodiments, probes utilizing RF emitters on the tip (capable of beingtracked by the LPS) can be used for steering flexible probes inside thebody. In some embodiments, if the LPS is not yet functional forlocalization, then localization can be performed using anelectromagnetic system such as the Aurora by Northern Digital. Aurora®is a registered trademark of Northern Digital Inc. For example, in thisinstance, an electromagnetic coil and RF emitters are both present inthe probe tip. Some embodiments can offer the option of LPS orelectromagnetic localization with steerable needles 7600. In thisembodiment of the invention, the surgeon can monitor the currentlocation on the medical image where the probe tip is currentlypositioned in real-time and activate RF electrodes to advance and steerthe probe tip in the desired direction using a joystick.

As discussed earlier, in some embodiments, the end-effectuator 30 caninclude a bayonet mount 5000 is used to removably couple the surgicalinstrument 35 to the end-effectuator 30 as shown in FIG. 15. Someembodiments can include a modification to the mount 5000 allowing theability to slide a clamping piece 6300 over the spinous process 6301without full exposure of the spinous process 6301. See example FIGS.30A-30B illustrating various embodiments of an end-effectuator 30including a modified mount 5000 with a clamping piece 6300 in accordancewith at least one embodiment of the invention. As shown, the clampingpiece 6300 comprises clamps 6302 including at least one beveled edge6310, and clamp teeth 6330.

In some embodiments, the surgeon would make a stab incision in themidline and then slide the clamps 6302 of the clamping piece 6300 downalong the sides of the spinous process 6301, pushing tissue away as thetip of the clamping piece is advanced. In some embodiments, the leadingedge of the clamping mechanism 6300 would be beveled (see the leadingedges 6305 of each clamp 6302 of the clamping mechanism 6300), and havea shape similar to a periosteal elevator. This allows the clampingmechanism 6300 to separate the muscle tissue from the bony spinousprocess 6301 as it is advanced. In some embodiments, the leading edges6305 of the clamping mechanism 6300 can be electrified to enable it tomore easily slide through muscle and connective tissues to preventexcessive bleeding.

In some embodiments, a mechanism activated from farther back on theshaft (for example a turn screw 6320, or conventional spring, etc.) canbe activated to deploy clamp teeth 6330 on the clamps 6302. The samemechanism or another mechanism would close and compress the clamps 6302together to firmly secure the clamping mechanism 6300 to the spinousprocess 6301 (see FIGS. 30B-30C). Additionally, in some embodiments, ascrew 6340 aligned with the handle 6350 could deploy to thread into thespinous process 6301 (see for example, FIG. 30C).

The embodiments as described above and shown in FIGS. 30A-30C would beespecially well suited to percutaneous pedicle screw-rod surgery becausethe hole made for mounting the clamping mechanism 6300 could also beused as the hole for inserting the conventional rod to interconnect theconventional pedicle screw heads. Further, the embodiments as describedabove and shown in FIGS. 30A-30C could also be useful for mounting amarker tree to other bony prominences, such as transverse processes,long bones, skull base, or others.

FIGS. 31 and 32 illustrate embodiments of clamping piece 6300 actuationon a spinous process 6301 in accordance with some embodiments of theinvention. In some embodiments, the mechanism for deploying the clampteeth 6330 could be comprised of a hollow tool tip 6360 containing teeth6330 that are to one side of the hollow cavity 6370 during insertion,but are forced toward the opposite side when the mechanism is deployed,such that the embedded teeth penetrate the bone (see the illustration ofpenetrated teeth 6330 a in FIG. 31).

FIG. 32 shows an alternative embodiment of the clamping piece 6300actuation on a spinous process 6301. As shown, the groups of teeth 6330are attached to rods 6365 that run down the hollow cavities 6360 a ofthe hollow tool tips 6360. These rods 6365 pivot farther up the handle6350 (pivot point not pictured) and the clamp teeth 6330 are forcedtogether. For example, in some embodiments, rods 6365 are driven intothe hollow cavity 6360 a of the hollow tool tip 6360 on the side awayfrom the bone, forcing the clamp teeth 6330 against and into the bone(for example, see the penetrated teeth 6330 a in FIG. 32).

As described above, the opaque markers 730 must be included in a CT scanof the anatomy. However, it is desirable to crop CT scans as close aspossible to the spine to improve resolution. In some embodiments,instead of using markers 730 near where the active markers 720 arelocated, an alternative is to have a rigid extension containing opaquemarkers 730 that are temporarily attached near the spine when the scanis taken. In some embodiments, the clamping piece 6300 can be coupledwith, or otherwise modified with a targeting fixture 690. For example,FIG. 33A illustrates a clamping piece 6300 modified with a targetingfixture 690 including a temporary marker skirt 6600 in accordance withat least one embodiment of the invention, and FIG. 33B illustrates aclamping piece 6300 modified with a targeting fixture 690 as shown inFIG. 33A with the temporary marker skirt 6600 detached in accordancewith at least one embodiment of the invention. As shown, the temporarymarker skirt 6600 includes radio-opaque markers 730 in a temporary“skirt” around the base of the clamping device 6300. The design of thetemporary marker skirt 6600 and clamping device 6300 must be such thatthe markers 730 in the skirt 6600 have known locations relative to themarkers 720 for tracking that are farther away. Once the scan is taken,the opaque markers 730 are not needed. Therefore, in some embodiments,by depressing a conventional release, the skirt 6600 can be removed soit will not be in the way of the surgeon (see for example FIG. 33B).

In some embodiments, it may also be desirable to mount the targetingfixture 690 to another piece that is already rigidly attached to thepatient 18. For example, for deep brain stimulation or other brainprocedure where the patient 18 is positioned in a Mayfield head holder,the head holder could serve as an attachment point for the targetingfixture 690. Since the head holder 6700 and skull form a rigid body, itis possible to track the head holder 6700 under the assumption that theskull moves the same amount as the head holder 6700. Further, in someembodiments of the invention, a surveillance marker (such assurveillance marker 710 as illustrated in FIG. 3) could be used. Forthis targeting fixture 690, active 720 and radio-opaque 730 markerswould be rigidly attached to the head holder 6700. The radio-opaquemarkers 730 need only be in position when the scan (CT, MRI, etc.) istaken and could subsequently be removed. The active markers 720 need notbe in position when the scan is taken but could instead be snapped inplace when it is necessary to begin tracking. For example, FIG. 34 showsone possible configuration for active 720 and radio-opaque markers 730attached to a Mayfield frame 6700 in accordance with one embodiment ofthe invention. As with other targeting fixtures 690, it is required thatthree or more radio-opaque markers 730 and three or more active markers720 are attached to same rigid body.

One problem with some robotic procedures is that the guide tube 50 mustbe physically rigidly mounted to the robot's end-effectuator, andtherefore mounting one or more dilator tubes can be challenging. Toaddress this problem, in some embodiments, dilators can be placed overthe central guide-tube 50 without removing the robot end-effectuator 30.For example, some embodiments can include an end-effectuator 30 thatincludes at least one dilator tube 6800, 6810. For example, FIG. 35shows end-effectuator 30 that includes nested dilators 6805 inaccordance with at least one embodiment of the invention. As shown, anested set 6805 of two or more disposable or non-disposable dilators6800, 6810 can be mounted onto the robot's end-effectuator 30. In someembodiments, each dilator 6800, 6810 may have its own removableconventional handle that allows a surgeon or an automated mechanism toforce the dilator down into soft tissue. Some embodiments could includeadditional dilators, for example, a nested set of three dilators of 7mm, 11 mm, and 14 mm diameter (not shown) may be useful for creating aportal for minimally invasive screw insertion or application of asurgical implant. In some embodiments, each dilator 6800, 6810 can havegreater length as it is closer to the central guide tube 50, allowingthe more central tube 50 to be advanced without radially advancing thedilator tubes 6800, 6810 out further.

In some further embodiments, the system 1 can include an end-effectuator30 that is coupled with at least one cylindrical dilator tube 6900. Forexample, FIGS. 36A-36C illustrate various embodiments of anend-effectuator 30 including cylindrical dilator tubes 6900 inaccordance with at least one embodiment of the invention. As shown, insome embodiments, the cylindrical dilator tubes 6900 can be formed fromtwo-halves that snap together. In some embodiments, the cylindricaldilator tubes 6900 can be formed from two-halves that snap together, andin some embodiments, the two-halves snap together over a previousdilator tube 6900. In some embodiments, the tubes 6900 can be fashionedso that they are strong in resisting radial compression, but notnecessarily strong in resisting radial expansion (since their opposingforce will be the resisting soft tissues). In some embodiments, thetubes 6900 can also benefit from a mechanism for temporarily attaching aconventional handle at the proximal end for easy insertion then removalof the handle following insertion. Moreover, some embodiments include amechanism for grasping and extracting each tube 6900 or a cluster oftubes 6900, or for attaching one or more tubes 6900 to the central guidetube 50. As depicted in FIG. 36B and 69C, when the robot'send-effectuator 30 is raised (following the tube 6900 insertion depictedin FIG. 36B), the tube 6900 or cluster of tubes 6900 is extracted withit, leaving behind the outermost dilator 6910 a and forming a corridorfor surgery. Further, in some embodiments, the surgeon can send therobot's end-effectuator 30 to coincide with the infinite vector definingthe desired trajectory, but above the patient 18. In some embodiments,the surgeon then sends the robot's end-effectuator 30 down this vectoruntil the tip of the central guide pin or tube 50 is ready to penetratesoft tissue. In some embodiments, a starter incision may be made to helpthe central guide tube 50 penetrate the tissue surface. In someembodiments, the surgeon continues to send the robot's end-effectuator30 down the trajectory vector, penetrating soft tissue, until the targetis reached (for example, when the tube 50 abuts bone of a targetregion). Then, in some embodiments, while the robot 15 holds the centraltube 50 steady, each sequential dilator 6900 is slid down the centraltube 50 over the previous dilator 6900. When desired dilation iscomplete, in some embodiments, the proximal end of the dilator tube 6900may be secured to the patient 18 (or external assembly), and the centraltube 50 and all but the outermost dilator tube 6910 would be removed.

Some embodiments include tubes 6900 that comprise a polymeric material.In some embodiments, the tubes 6900 can include at least one eitherradiolucent or radio-opaque material. In some embodiments, dilators 6900may be radio-opaque so that their position may be easily confirmed byx-ray. Further, in some embodiments, the outermost dilator 6910 may beradiolucent so that the position of pathology drawn out through thetube, or implants, or materials passed into the patient through thetube, may be visualized by x-ray.

As described earlier, in some embodiments, the use of conventionallinear pulse motors within the surgical robot 15 can permitestablishment of a non-rigid position for the end-effectuator 30 and/orsurgical instrument 35. In some embodiments, the use of linear pulsemotors instead of motors with worm gear drive enables the robot 15 toquickly switch between active and passive modes.

The ability to be able to quickly switch between active and passivemodes can be important for various embodiments. For example, if there isa need to position the robot 15 in the operative field, or remove therobot 15 from the operative field. Instead of having to drive the robot15 in or out of the operative field, in some embodiments, the user cansimply deactivate the motors, making the robot 15 passive. The user canthen manually drag it where it is needed, and then re-activate themotors.

The ability to be able to quickly switch between active and passivemodes can be important for safe zone surgery. In some embodiments, theuser can outline a region with pathology (for example a tumor 7300) onthe medical images (see for example FIG. 37 showing the displayed tumor7310 on display means 29). In some embodiments, algorithms may then beimplemented where the robot 15 switches from active to passive mode whenthe boundary of the region is encountered. For example, FIG. 37 showsthe boundary region 7320 within the patient 18 displayed as region 7325on the display means. Anywhere outside the boundary 7320, the robotbecomes active and tries to force the end-effectuator 30 back toward thesafe zone (i.e. within the boundary 7320). Within the boundary 7320, therobot 15 remains passive, allowing the surgeon to move the tool (such asdrill bit 42) attached to the end-effectuator 30.

In some further embodiments, the user can place restrictions (throughsoftware) on the range of orientations allowed by the tool within thesafe zone (for example, boundary 7320, and displayed as boundary 7325 inFIG. 37). In some embodiments, the tool can only pivot about a pointalong the shaft that is exactly at the level of the skin. In thisinstance, the robot 15 freely permits the surgeon to move in and out andpivot the end-effectuator 30, but does not allow left-right orfront-back movement without pivoting. For example, in some embodiments,if the surgeon wants to reach a far left point on the tumor 7300, thesurgeon must pivot the tool about the pivot point and push it to theappropriate depth of insertion to satisfy the boundary 7320 conditionsand force the tip (for example, the tip of the drill bit 42) to thatlocation. This type of limitation can be valuable because it can preventthe surgeon from “ripping” tissue as the drill is moved around todestroy the tumor 7320. Further, it also allows the surgeon to access asafe zone farther distal while keeping clear of a critical structurefarther proximal.

Some embodiments include curved and/or sheathed needles for nonlineartrajectory to a target (for example, such as a tumor 7320 describedearlier). In some embodiments, with a curved trajectory, it is possibleto approach targets inside the body of a patient 18 that might otherwisebe impossible to reach via a straight-line trajectory. For example, FIG.38A illustrates a robot end-effectuator 30 coupled with a curved guidetube 7400 for use with a curved or straight wire or tool 7410 inaccordance with at least one embodiment of the invention. In someembodiments, by forcing a curved or straight wire or tool 7410 throughthe curved guide tube 7400, at least some curvature will be imparted tothe wire or tool 7410. In some embodiments, the curved or straight wireor tool 7410 may comprise a compliant wire capable of forming to thecurvature of the guide tube 7400. In some other embodiments, the curvedor straight wire or tool 7410 may comprise a non-compliant wire, capableof substantially retaining its shape after entering and exiting theguide tube 7400. A disadvantage of using a very compliant wire is thatthe tissues that it encounters may easily force it off the desired path.A disadvantage of using a very non-compliant wire is that it would bedifficult to achieve a useful amount of curvature. Further, forcing astraight wire of intermediate compliance through a curved guide tube7400 may produce some curvature of the wire, but less curvature thanthat of the guide tube 7400. It is possible to mathematically orexperimentally model the mechanical behavior of the wire 7410 todetermine how much curvature will be imparted. For example, by knowingthe orientation of the guide tube 7400, in some embodiments, the robotmay be used to accurately guide the curved wire 7410 to a desired targetby using computerized planning to predict where the wire 7410 would endup as it traveled through tissue. Further, in some embodiments a verynon-compliant wire or tool 7410 can be manufactured in the shape of anarc with a specific radius of curvature, and then fed through a guidetube 7400 with the same radius of curvature. By knowing the orientationof the guide tube 7400 (i.e. substantially the same as wire or tool7410), computerized planning can be used to predict where the wire ortool 7410 would end up as it traveled through tissue.

Some other embodiments may use a straight guide tube 50 with a wire ortool 7410 that may be curved or straight. For example, FIG. 38Billustrates a robot end-effectuator 30 coupled with a straight guidetube 50 for use with a curved or straight wire or tool 7405, 7410 inaccordance with at least one embodiment of the invention. Some surgicalmethods may use curved needles 7410 that are manually positioned. Ingeneral, the needles consist of a rigid, straight outer guide tubethrough which is forced an inner needle 7405 with tendency to take on acurved shape. In existing manual devices, the inner needle 7405 iscomprised of nitinol, a shape memory alloy, and is formed withsignificant curvature. This curved needle 7410 is flattened and then fedthrough the outer guide tube. When it exits the other end of the guidetube, it bends with significant force back toward its original curvedconfiguration. Such a system could be adapted for use with the robot 15if the curvature of the exiting portion of the needle per unit measureexiting is known, if the radial position of the curved needle 7410relative to the straight housing is known. In some embodiments, theradial position of the curved needle 7410 can be determined by usingmarks placed on the curved and straight portions, or through anon-circular cross-section of the straight guide tube and curved needle7410 (for example, square cross-section of each). In this instance, insome embodiments, it would then be possible to preoperatively plan thepath to the target (such as a tumor 7300) and then adjust the robot 15to guide the curved wire or tool 7410 through this path. In someembodiments, the system 1 can include the ability to electricallystimulate distally while advancing a wire (for example, such as wire7405, 7410) through soft tissue. For example, some embodiments include aguide tube 7500 capable of being coupled to the robot 15 byend-effectuator 30 that is insulated along its entire shaft but has anelectrode 7510 on or near the tip (see for example FIG. 39). In someembodiments, the use of the tube 7500 to perform electromygraphy (“EMG”)can enable the system 1 to detect whether nerves come in contact withthe guide tube 7500 as the guide tube 7500 is advanced. Some alternativeembodiments can include a conventional pin (for example, stainless steelpins such as Kirschner-wires) instead of a tube 7500, insulated alongits shaft but not at the tip. In some embodiments, the wire could beconnected to a stimulator outside the body and would have the ability tostimulate distally while advancing the pin through soft tissue. In someembodiments, stimulation would allow the ability to identify criticaltissue structures (i.e., nerves, plexus).

In some further embodiments, a portion of the leading edge of the guidetube 7500 may be insulated (i.e. comprise a substantiallynon-electrically conductive area), and a portion of the leading edge maybe uninsulated (i.e. the region is inherently electrically conductivearea). In this instance, it can be possible to determine the radialdirection of the tube 7500 that is closest to the nerve by watching theresponse as the tube 7500 is rotated. That is, as the tube 7500 isrotated, the EMG nerve detection will have the most pronounced responsewhen the uninsulated portion is nearest the nerve, and the leastpronounced response when the uninsulated portion is farthest from thenerve. In some embodiments, it would then be possible for the user tomanually steer the robot 15 to automatically steer the tube 7500 fartheraway from the nerve. In addition, this modified tube 7500 could have aconventional fan-like retractor (not shown) that can be deployed togently spread the underlying muscle fibers, thereby making an entrypoint for disk removal, or screw insertion. In some embodiments, thecombination of EMG and gentle retraction can enhance the safety andoutcomes of robotic assisted spinal surgery.

As described above, one way of taking advantage of the directionalelectromyographic response is for the user to manually rotate the tube7500. In some other embodiments, the tube 7500 can be to continuouslyoscillated back and forth, rotating about its axis while potentials aremonitored. In some embodiments, to achieve the same function withoutrotating the tube 7500, the leading edge of the tube 7500 could haveconductive sections that could be automatically sequentially activatedwhile monitoring potentials. For example, in some embodiments, an arrayof two, three, four, or more electrodes 7510 (shown in FIG. 39) can bepositioned around the circumference of the leading edge of the tube7500. As shown in FIG. 39, regions 7511 between the electrodes 7510 areinsulated from each other (because the outer surface of 7500 isinsulated). In some embodiments, the electrodes 7510 can be sequentiallyactivated at a very high rate while recording potentials, andcorrelating which electrode produces the greatest response.

Some embodiments can include a steerable needle capable of being trackedinside the body. For example, U.S. Pat. No. 8,010,181, “System utilizingradio frequency signals for tracking and improving navigation of slenderinstruments during insertion in the body”, herein incorporated byreference, describes a steerable flexible catheter with two or more RFelectrodes on the tip, which are used for steering. According to themethod described in U.S. Pat. No. 8,010,181, the side or sides of thetip where the electrodes emit RF have less friction and therefore theprobe will steer away from these sides.

In some embodiments of the invention, a steerable needle 7600 can becoupled with the system 1. In some embodiments, the system 1 can includea steerable needle 7600 coupled with the robot 15 through a coupledend-effectuator 30, the steerable needle 7600 capable of being trackedinside the body of a patient 18. For example, FIG. 40 illustrates asteerable needle 7600 in accordance with at least one embodiment of theinvention. In some embodiments, steerable needle 7600 can comprise aplurality of flattened angled bevels 7605 (i.e. facets) on the tip ofthe probe, with each flat face of each bevel 7605 having an RF electrode7610. A magnetic coil sensor 7620 embedded within the needle 7600 canenable localization of the tip adjacent to the electrodes 7610. In someembodiments, RF can be used for steering, whereas localization would useelectrodes 7610 with the magnetic coil sensor 7620. Some embodiments asdescribed may use off-the-shelf electromagnetic localization system suchas the Aurora® from Northern Digital, Inc. (http://www.ndigital.com),which has miniature coils capable of fitting inside a catheter.

During surgical procedures, pedicle screws or anterior body screws areinserted in two locations. However, there is a chance of failure due toscrew pullout. To enhance resistance to pullout, screws are angledtoward each other. For example, some embodiments can includeintersecting and interlocking bone screws 7700 such as those illustratedin FIG. 41, illustrating one embodiment of intersecting and interlockingbone screws 7700 in accordance with at least one embodiment of theinvention. As shown, bone screws 7700 can be coupled and can intersectand interlock 7720. In some embodiments, the intersecting andinterlocking bone screws 7700 as shown can be removed without destroyinga large area of bone.

Some embodiments of the system 1 can include conventional trackingcameras with dual regions of focus. For example, camera units such asOptotrak® or Polaris® from Northern Digital, Inc., can be mounted in abar so that their calibration volume and area of focus are set.Optotrak® or Polaris® are registered trademarks of Northern Digital, Inc(see for example FIG. 48 showing camera bar 8200). In some embodiments,when tracking the robot 15 and targeting fixture 690 with opticaltrackers (for example, active markers 720), maintaining markers 720within the center of the volume can provide the best focus. However, itis not possible for both the targeting fixture's 690 markers and therobot's 15 markers to be substantially centered simultaneously, andtherefore both are offset from center by substantially the samedistance.

In some embodiments, one solution to this issue is to set up two pairsof cameras 8200 with one camera shared, that is, cameras 1 and 2 formone pair, and cameras 2 and 3 form another pair. This configuration isthe same as the Optotrak® system (i.e., three cameras in a single bar),however, the Optotrak® only has one volume and one common focal point.Conversely, some embodiments of the invention would be tuned to have twofocal points and two volumes that would allow both the targeting fixture690 and the robot 15 to be centered at the same time. In someembodiments, the orientations of the lateral cameras can be adjusted byknown amounts with predictable impact on the focal point and volume.

In a further embodiment of the invention, two separate camera units (forexample, two Polaris® units) can be mounted to a customized conventionalbracket fixture including adjustment features (not shown). In someembodiments, this fixture would be calibrated so that the vectorsdefining the directions of the volumes and distance to focal point canbe adjustable by known amounts. In some embodiments, the user could thenpoint one Polaris® unit at the robot's markers, and the other Polaris®unit at the targeting fixture's 690 markers 720. The position of theadjustment features on the bracket would tell the computer what thetransformation is required to go from one camera's coordinate system tothe other.

In some further embodiments, the cameras 8200 (such as Optotrak® orPolaris®) focused on a particular region could be further improved by aconventional automated mechanism to direct the cameras 8200 at thecenter of the target. Such a method would improve accuracy because ingeneral, image quality is better toward the center of focus than towardthe fringes. In some embodiments, conventional motorized turrets couldbe utilized to adjust azimuth and elevation of a conventional bracketassembly for aiming the cameras 8200 (and/or in conjunction withmovement of cameras 8200 on camera arm 8210 as shown in FIG. 48). Insome embodiments, feedback from the current location of active markers720 within the field of view would be used to adjust the azimuth andelevation until the camera 8200 points directly at the target,regardless of whether the target is the center (mean) of the markers 720on the robot 15, the center of markers 720 on the targeting fixture 720,or the center of all markers 720. In some embodiments, such a methodwould allow the center of focus of the cameras 8200 to continuously moveautomatically as the patient 18 or robot move, ensuring the optimalorientation at all times during the procedure.

Some embodiments can include a snap-in end-effectuator 30 with attachedtracking fixtures 690 (including active markers 720). For example, someembodiments include snap-in posts 7800 attached to the end-effectuator30 and tracking fixtures 690. In some embodiments, the snap-in posts7800 can facilitate orienting tracking markers 720 to face cameras 8200in different setups by allowing markers 720 to be mounted to eachend-effectuator 30. FIG. 42A-42B illustrates configurations of a robot15 for positioning alongside a bed of a patient 18 that includes atargeting fixture 690 coupled to an end-effectuator 30 using a snap-inpost 7800. In some embodiments, with the robot 15 in a typicalconfiguration alongside a bed with the patient's 18 head toward theleft, one end-effectuator 30 could have right-facing markers 720(fixture 690) (illustrated in FIG. 42A) for cameras 8200 positioned atthe foot of the bed. In some embodiments, the same type ofend-effectuator 30 could have left-facing markers 720 (fixture 690) forcameras 8200 positioned at the head of the bed (illustrated in FIG.42B). In some embodiments, the fixtures 690 are mounted where they wouldbe closer to the cameras 8200 than the end-effectuator 30 so that thesurgeon does not block obscure the markers 720 from the camera whenusing the tube 50. In some further embodiments, each interchangeableend-effectuator 30 could include conventional identificationelectronics. For example, in some embodiments, each interchangeableend-effectuator 30 could include an embedded conventional chip and apress-fit electrical connector. In some embodiments, when the system 1includes a snap-in end-effectuator 30 with attached tracking fixtures690, the computer 100 may recognize which end-effectuator is currentlyattached using the identification electronics. In some embodiments, whenthe system 1 includes a snap-in end-effectuator 30 with attachedtracking fixtures 690, the computer 100 may recognize whichend-effectuator is currently attached using the identificationelectronics, and apply stored calibration settings.

The robot system 1 contains several unique software algorithms to enableprecise movement to a target location without requiring an iterativeprocess. In some embodiments, an initial step includes a calibration ofeach coordinate axis of the end-effectuator 30. During the calibration,the robot 15 goes through a sequence of individual moves while recordingthe movement of active markers 720 that are temporarily attached to theend-effectuator (see FIG. 43). From these individual moves, which do nothave to fall in a coordinate system with orthogonal axes, the requiredcombination of necessary moves on all axes is calculated.

In some embodiments, it is possible to mount optical markers 720 fortracking the movement of the robot 15 on the base of the robot 15, thento calculate the orientation and coordinates of the guide tube 50 basedon the movement of sequential axes. The advantage of mounting markers720 on the base of the robot 15 is that they are out of the way and areless likely to be obscured by the surgeon, tools, or parts of the robot.However, the farther away the markers 720 are from the end-effectuator30, the more the error is amplified at each joint. At the other extreme,it is possible to mount the optical markers 720 on the end-effectuator30 (as illustrated in FIG. 43). The advantage of mounting markers 720 onthe end-effectuator is that accuracy is maximized because the markers720 provide feedback on exactly where the end-effectuator 30 iscurrently positioned. A disadvantage is that the surgeon, tools, orparts of the robot 15 can easily obscure the markers 720 and then theend-effectuator's 30 position in space cannot be determined.

In some embodiments, it is possible to mount markers 720 at eitherextreme or at an intermediate axis. For example, in some embodiments,the markers 720 can be mounted on the x-axis 66. Thus, when the x-axis66 moves, so do the optical markers 720. In this location, there is lesschance that the surgeon will block them from the cameras 8200 or thatthey would become an obstruction to surgery. Because of the highaccuracy in calculating the orientation and position of theend-effectuator 30 based on the encoder outputs from each axis, it ispossible to very accurately determine the position of theend-effectuator 30 knowing only the position of the markers on thex-axis 66.

Some embodiments include an algorithm for automatically detecting thecenters of the radio-opaque markers 730 on the medical image. Thisalgorithm scans the medical image in its entirety looking for regionsbounded on all sides by a border of sufficient gradient. If furthermarkers 730 are found, they are checked against the stored locations andthrown out if outside tolerance.

Some biopsy procedures can be affected by the breathing process of apatient, for example when performing a lung biopsy. In some procedures,it is difficult for the clinician to obtain a sample during the correctbreathing phase. The use of tracking markers 720 coupled to a bone ofthe patient cannot alone compensate for the breathing induced movementof the target biopsy region. Some embodiments include a method ofperforming a lung biopsy with breathing correction using the system 1.Currently, for radiation treatment of lung tumors, breathing ismonitored during CT scan acquisition using a “bellows” belt (see forexample CT scanner 8000 in FIG. 44, with bellows image 8010. The bellowsmonitors the phase of breathing, and when the clinician tells thepatient to hold their breath, CT scan of the patient 18 is performed.The bellows output 8010 shows the phase in which the CT was taken.Later, targeted radiation bursts can be applied when the lung is in theright position as monitored by the bellows during the treatment phase. ACT scan is taken while the bellows monitors the breathing phase and whenthe patient held their breath during the CT scan. Later, radiationbursts are applied instantaneously when that same phase is reachedwithout requiring the patient 18 to hold their breath again.

Some embodiments include a method of performing a lung biopsy withbreathing correction using the system 1. In some embodiments, a trackingfixture 690 is attached to the patient 18 near biopsy site and bellowsbelt on the patient's 18 waist. In some embodiments, a CT scan of thepatient 18 is performed with the patient holding their breath, and whilemonitoring the breathing phase. In some embodiments, a clinician locatesthe target (for example, a tumor) on the CT volume, and configures therobot 15 to the target using at least one of the embodiments asdescribed earlier. In some embodiments, the robot 15 calibratesaccording to at least one embodiment described earlier. In someembodiments, the robot 15 moves into position above the biopsy sitebased the location of at least one tracking marker 720, 730. In someembodiments, the bellows belt remains in place, whereas in otherembodiments, the markers 720, 730 on the patient 18 can track thebreathing phase. In some embodiments, based on the bellows or trackingmarkers 720, 730, the computer 100 of the computing device withinplatform can use robotic guidance software to send a trigger during thecalibrated breathing phase to deploy a biopsy gun to rapidly extract abiopsy of the target (such as a tumor). In some embodiments, aconventional biopsy gun (or tool, such as biopsy gun tip 8100 in FIG.45) could be mounted in the robot's end-effectuator 30 and activated bya conventional mechanism (such as for example, by a toggled digitaloutput port). For example, as shown, the biopsy gun tip 8100 cancomprise a biopsy needle 8110 including a stroke length 8120, a samplingwindow 8130 and a biopsy tip 8140. In some embodiments, the biopsyneedle 8110 in the biopsy gun tip 8100 can be mounted to theend-effectuator 30. In some embodiments, the biopsy needle 8110 can beinserted (under guidance by the robot 15) at least partially into thesuperficial tissues near the target (for example, the moving lungtumor). In some embodiments, the biopsy gun tip 8100 can fire asdirected by a software trigger, requiring only a small penetration toretrieve the biopsy.

Deep brain stimulation (“DBS”) requires electrodes to be placedprecisely at targets in the brain. Current technology allows CT and MRIscans to be merged for visualizing the brain anatomy relative to thebony anatomy (skull). It is therefore possible to plan trajectories forelectrodes using a 3D combined CT/MRI volume, or from CT or MRI alone.Some embodiments include robot 15 electrode placement for asleep deepbrain stimulation using the system 1 where the acquired volume can thenbe used to calibrate the robot 15 and move the robot 15 into position tohold a guide 50 for electrode implantation.

In some embodiments, a Mayfield frame 6700 modified including onepossible configuration for active and radio-opaque markers (shown inFIG. 34 in accordance with one embodiment of the invention) can be usedfor electrode placement for asleep deep brain stimulation. In someembodiments, the active markers 720 do not need to be attached at thetime of the scan as long as their eventual position is unambiguouslyfixed. In some embodiments, the radio-opaque markers 730 can be removedafter the scan as long as the relative position of the active markers720 remains unchanged from the time of the scan. In some embodiments,the marker 730 can be a ceramic or metallic sphere, and for MRI, asuitable marker is a spherical vitamin E capsule. In some embodiments,the end-effectuator 30 can include an interface for feeding in aconventional electrode cannula and securing the electrode housing to theskull of the patient 18 (for example, using a Medtronic StimLoc® leadanchoring device to the skull). StimLoc® is a trademark of Medtronic,Inc., and its affiliated companies.

In some embodiments, the system 1 can perform the method steps 7910-7990as outlined in FIG. 46 for DBS electrode placement. As show, in someembodiments, the patient 18 can receive an MRI 7910, and the target andtrajectory can be planned 7915. Surgery can be initiated under generalanesthesia 7920, and the head frame (as shown in FIG. 34) can beattached to the patient 18 with three screws in the skull 7925. In someembodiments, a CT scan can be performed 7930, and the previouslyobtained MRI 7910 can be merged with the CT scan 7935. During the CTscan, software can automatically register the anatomy relative to themarkers 720, 730 that are mounted on the head holder. In someembodiments, the robot 15 can direct a laser at the skin of the patient18 to mark flaps 7940. In some embodiments, the skin of the patient 18can be prepared and draped 7945, and scalp flaps can be prepared 7950.As shown, in some embodiments, the robot 15 can laser drill entry holes7955, and the StimLoc can be secured bilaterally 7960 (permanentimplant, 2 screws per electrode). In some embodiments, the robot 15 canauto-position a conventional electrode guide adjacent to entry point ata fixed (known) distance from target 7965. In some embodiments, the duracan be opened, a cannula and electrode inserted, and a StimLoc clip canbe positioned 7970. In some embodiments, steps 7965, 7970 are repeatedfor the other side of the patient's skull 7975. In some embodiments, averification CT scan is performed 7980, a cap is placed over theStimLoc, and the flaps are closed.

In some embodiments, the robot system 1 includes at least one mountedcamera. For example, FIG. 48 illustrates a perspective view of a robotsystem including a camera arm in accordance with one embodiment of theinvention. In some embodiments, to overcome issues with line of sight,it is possible to mount cameras for tracking the patient 18 and robot 15on an arm 8210 extending from the robot. As shown in FIG. 48, in someembodiments, the arm 8210 is coupled to a camera arm 8200 via a joint8210 a, and the arm 8210 is coupled to the system 1 via joint 8210 b. Insome embodiments, the camera arm 8200 can be positioned above a patient(for example, above a patient 18 lying on a bed or stretcher as shown inFIG. 48). In this position, in some embodiments, it might be less likelyfor the surgeon to block the camera when the system 1 is in use (forexample, during a surgery and/or patient examination). Further, in someembodiments, the joints 8210 a, 8210 b can be used to sense the currentposition of the cameras (i.e. the position of the camera arm 8200).Moreover, in some embodiments, the exact position of the end-effectuator30 in the camera's coordinate system can be calculated based onmonitored counts on each robot axis 66, 68, 70, 64, and in someembodiments, the cameras 8200 would therefore only have to track markers720 on the patient 18.

Some embodiments include an arm 8210 and camera arm 8200 that can foldinto a compact configuration for transportation of the robot system 1.For example, FIG. 49A illustrates a front-side perspective view of arobot system including a camera arm in a stored position, and FIG. 49Billustrates a rear-side perspective view of a robot system including acamera arm in a stored position in accordance with one embodiment of theinvention.

Some embodiments can include methods for prostate 8330 immobilizationwith tracking for imaged-guided therapy. In some embodiments, to enablethe insertion of a needle (7405, 7410, 7600, 8110 for example) into theprostate 8330 utilizing 3D image guidance, a 3D scan of the prostate8330 relative to reference markers 720, 730 or other tracking system isneeded. However, the prostate 8330 is relatively mobile and can shiftwith movement of the patient 18. In some embodiments, it may be possibleto immobilize the prostate 8330 while also positioning and securingtracking markers 720 in close proximity to improve tracking and imageguidance in the prostate 8330.

The prostate 8330 is anatomically positioned adjacent to the bladder8320, the pubic bone 8310, and the rectum 8340 (see for example FIG. 50showing a lateral illustration of a patient lying supine, depicting thenormal relative positions of the prostate 8330, rectum 8340, bladder8320, and pubic bone 8310). This position facilitates entrapment of theprostate 8330, especially when it is enlarged, against the bladder 8320and pubic bone 8310 via anterior displacement applied within the rectum8340. In some embodiments, displacement could be applied using a balloon8410, a paddle 8420, or a combination of the two elements. For example,FIG. 51A shows a lateral illustration of a patient lying supine, showinghow inflation of a balloon can cause anterior displacement of theprostate 8330 toward the pubic bone 8310, and a controllable amount ofcompression against the pubic bone 8310 in accordance with oneembodiment of the invention. Further, FIG. 51B shows a lateralillustration of a patient lying supine, showing how shifting of a paddlein the rectum 8340 can cause anterior displacement of the prostate 8330toward the pubic bone 8310, and a controllable amount of compressionagainst the pubic bone 8310 in accordance with one embodiment of theinvention.

In some embodiments, the balloon 8410 has the advantage that it can beinserted into the rectum 8340 un-inflated, and then when inflated. Insome embodiments, it will displace the wall of the rectum 8340 andprostate 8330 laterally toward the pubic bone 8310. In some embodiments,a paddle 8420 can cause lateral displacement of the rectal wall andprostate 8330 if a pivot point near the anus is used.

In some embodiments, it is possible to configure a device consisting ofa balloon 8410 and paddle 8420 such that fiducials are embedded in thedevice, with these fiducials being detectable on the 3D medical image(for instance, such as MRI). For example, FIG. 52 shows a sketch of atargeting fixture and immobilization device to be used for tracking theprostate 8330 during image-guided surgical procedures in accordance withone embodiment of the invention. As shown, active tracking markers 720can be rigidly interconnected to the paddle element 8420 such that thesetracking markers 720 protrude from the rectum 8340 and are visible totracking cameras (for example, 8200) during the medical procedure. Forexample, FIG. 53 shows an illustration of the device as illustrated inFIG. 52, in place in the rectum 8340 with prostate 8330 compressed andimmobilized and tracking markers visible protruding caudal to the rectum8340 in accordance with one embodiment of the invention.

In some embodiments, in addition to applying lateral force from the sideof the rectum 8340, it is also possible to apply lateral force from theside of the abdomen of the patient 18. In some embodiments, thissecondary lateral force, used in conjunction with the force from therectal wall, may assist in keeping the prostate 8330 immobilized.Additionally, it can serve as a support to which the tracking markers720 are attached, and can serve as a support to which the rectalpaddle/balloon 8420, 8410 can be attached for better stabilization. Insome embodiments, the abdominal support can consist of a piece thatpresses from anterior toward posterior/inferior to press against the topof the bladder 8320 region. For example, conventional straps or piecesthat encircle the legs can provide additional support. Since theabdominal shape and leg shape varies among patients, some customizationwould be beneficial. In some embodiments, adjustable straps and supportsmade of thermoplastic material could be utilized for customization. Insome embodiments, commercially available thermoplastic supports (forexample, from Aquaplast Inc) can be used. In some embodiments, thesupports are formed by first dipping the support material in hot waterto soften it, then applying the support to the patient's skin andmolding it. After removing the support material from the hot water, thetemperature is low enough that it does not burn the skin, but is warmenough that the support material remains soft for 1-5 minutes. In someembodiments, when the support cools, it maintains the skin contoursagainst which it has been formed. In some embodiments, this type ofsupport could be made for immobilizing the prostate 8330 shaped likemoldable briefs. In this instance, the support would be dipped in hotwater and then external straps and/or manual pressure would be appliedto force the support device to press down toward the prostate 8330.Further, in some embodiments, the support could be manufactured in twohalves, formed so that it is molded while two halves are tied together,and then removed (untied) when cool (so that it can later be reattachedin the same configuration during the procedure).

In some embodiments, the combination of the elements as described above(including balloon 8410 and/or paddle 8420, enables real-time trackingof the prostate 8330, and manual or robotically assisted insertion ofneedles (for example, 7405, 7410, 7600, 8110) into the prostate 8330based on targeting under image guidance. In some embodiments, theprocedure can include the conventional abdominal support device asdescribed above. The device would be prepared by dipping in hot wateruntil soft, then applying to the patient such that gentle pressure ismaintained from anterior to posterior/inferior against the bladder 8320region and prostate 8330. In some embodiments, under palpation, thetracking device (paddle 8420 with coupled fixture 690 including markers720 illustrated in FIG. 52) would be inserted into the rectum 8340 withthe paddle 8420 and radio-opaque markers 730 adjacent to the prostate8330. In this instance, gentle pressure can be manually applied to theprotruding handle by the surgeon to maintain the position of theinterior paddle 8420. In some embodiments, the balloon 8410 is inflatedto maintain gentle compression against the prostate 8330, and toimmobilize the prostate 8330 against the pubic bone 8310. In someembodiments, if the conventional abdominal device is used, the abdominaldevice is interconnected to the rectal device at this point foradditional stability. In some embodiments, an MRI is obtained. Duringthe MRI, the active tracking markers 720 are not attached since they aremetallic. In some embodiments, sockets or other conventionalquick-connect mechanical device are present in the locations where themarkers 720 or marker tree (fixture 690) will later be inserted. In someembodiments, the MRI captures an image of the prostate 8330, and theradio-opaque markers 730 embedded in the handle 8425. In someembodiments, the MRI can be captured with the patient's legs down toallow the patient 18 to fit into the gantry of the scanner. In someembodiments, the patient 18 is positioned on the procedure table withlegs raised. Tracking markers 730 are snapped into the sockets on theprotruding handle or the marker tree 690 with markers 720 is otherwisefastened. In some embodiments, registration of the markers 730, 720 isachieved by software (for example, using one or more modules of thesoftware using the computing device), which automatically detects thepositions of the radio-opaque markers 730 on the medical image. In someembodiments, the known relative positions of the active tracking markers720 and the radio-opaque marker 730 fiducials synchronizes thecoordinate systems of the anatomy of the patient 18, tracking system andsoftware, and robot 15. In some embodiments, the surgeon planstrajectories for needle 7405 insertion into the prostate 8330 on themedical image, and the robot 15 moves the guide tube 50 to the desired3D location for a needle 7405 of known length to be inserted to thedesired depth.

Some embodiments can use a dual mode prostate 8330 tracking forimage-guided therapy. For example, in some embodiments, it is possibleto accurately track the prostate 8330 using a combination of twotracking modalities, including fiber optic tracking. For this alternatemethod to be used, an optical tracker (fiber optic probe 8700) wouldfirst be applied externally. This probe 8700 would be registered to the3D medical image (for example, using an MRI scan) in substantially thesame way as previously described, such as for the spine tracking usingCT imaging. In some embodiments, after registering and calibrating sothat the coordinate systems of the medical image and cameras 8200 aresynchronized, a means of updating and correcting for movement of theprostate 8330 can be used. In some embodiments, the probe 8700 cancomprise a fiber optic sensor with a Bragg grating. For example, FIG.54. illustrates a demonstration of a fibre Bragg grating (“FBG”)interrogation technology with a flexible fiber optic cable in accordancewith one embodiment of the invention. As shown the technology isavailable from Technobis Fibre Technologies, Uitgeest, Holland. As thefiber optic cable is bent by hand, the system accurately senses theposition to which the cable deforms. As depicted in FIG. 55, in someembodiments, the probe 8700 could be inserted into the urethra with thetip of the sensor positioned at the prostate 8330. Since the prostate8330 surrounds the urethra, a sensor such as probe 8700 positioned inthe urethra should show very accurately how the prostate 8330 moves. Asshown, the probe 8700 can be coupled with the fixture 690 includingmarkers 720, 730, and coupled to the computer 100 with optical trackerelectronics 8810 and fiber optic electronics 800 coupled to the computer100, coupled to the robot 15.

In some embodiments, markings 8910 (gradations) capable of beingvisualized on MRI can be placed on the outer shaft of the probe 8700(see for example, FIG. 56). In some embodiments, if the MRI is obtainedwhile the probe 8700 is in position in the urethra, it is possible todetermine which point or points along the length of the probe 8700represent key landmarks within the prostate 8330 (e.g., distal entry,proximal exit, midpoint). In some embodiments, these points can then betracked by the fiber optic electronics 8800 during the procedure. Insome embodiments, the points can then be used to adjust the coordinatesystem of the prostate 8330 so that the local coordinate system remainsproperly synchronized with the coordinate system of the optical trackingsystem even if the surrounding anatomy (specifically the anatomy towhich the tracking markers 720, 730 are attached) shifts relative to theprostate 8330. In other words, the position of the tracking markers 720,740 on the patient's skin surface gives an approximate estimate of wherethe prostate 8330 is currently located, and the fiber optic probe 8700(which is rigidly interconnected to the tracking fixture 690) correctsthis position to substantially improve accuracy and account for shiftingof the prostate 8330.

In some embodiments, image-guided therapy can be performed using one ormore of the embodiments as described. For example, in some embodiments,the fiber optic probe as depicted in FIG. 55 can include opticallyvisible 8900 and MRI visible 8910. In some embodiments, the probe 8700is inserted into the penis and advanced until the tip passes into thebladder 8320 (shown in FIG. 56). In some embodiments, the marking 8900,8910 will provide information about what section of the fiber optic ispositioned within the prostate 8330. In some embodiments, the depth ofinsertion is recorded based on visible markings 8900 on the proximal endthat has not entered the penis is recorded. In some embodiments, thisinformation can be used to check whether the probe 8700 has moved, or toreposition the probe 8700 if it is intentionally moved. In someembodiments, the proximal end may be secured (taped) to the penis toprevent advancement or withdrawal with patient 18 movement. In someembodiments, the distal end may have a feature to prevent it from easilysliding back out of the bladder 8320. For example, as shown in FIG. 57,some embodiments include a probe 8700 that comprises an inflatable tip8920. In some embodiments, the inflatable tip 8920 can be enlarged orflared in the area near the tip. In some embodiments the tip 8920comprises a balloon that is inflatable after the tip has passed into thebladder 8320, whereas in other embodiments, the tip 8920 comprisesconventional soft wings that deploy after the tip has passed into thebladder 8320. As shown in FIG. 57, in some embodiments, a targetingfixture 690 is attached to the patient 18 in the region of the perineum(or abdomen or other suitable surface). The targeting fixture hasembedded radio-opaque fiducial markers 730 that will show up on the MRI(or other 3D scan), and is equipped with a conventional quick-connectinterface that will later accept an attachment with active trackingmarkers 720. These tracking markers 720 do not need to be present yet,especially if they are not MRI compatible. The targeting fixture 690 canbe rigidly interconnected with the proximal end of the fiber optic probe8700.

In some embodiments, the patient 18 is positioned outside or in thegantry of the MRI scanner before scanning. In some embodiments, thefiber optic tracking system 9100 is briefly activated to record positionof the fiber optic probe 8700 along its entire length for laterreference (see FIG. 58). Once recorded, the electronic interface (8800)for the fiber optic tracking system 9100 may be disconnected and removedfrom the MRI area. In some embodiments, an MRI scan is obtained. Thescan must visualize the prostate 8330, the radio-opaque fiducials 730 onthe targeting fixture 690, and the markings 8910 that are present alongthe urethral tube that will be tracked with fiber optic probe 8700. Insome embodiments, the position of the prostate 8330 along the fiberoptic probe 8700 at the time of the scan is recorded from theradio-opaque markings 8910 on its surface.

In some embodiments, the patient is positioned on the procedure table,and optical tracking markers 720 are snapped into the targeting fixture(see FIG. 59) and activated. In some embodiments, registration of themarkers 720 is achieved by software (for example by one or more moduleswithin the device), which automatically detects the positions of theradio-opaque markers 730 on the medical image. The known relativepositions of the active tracking markers 720 and the radio-opaquefiducials 730 synchronizes the coordinate systems of the anatomy,tracking system, and robot 15. The fiber optic tracking system 9100 isactivated.

In some embodiments, the offset of the prostate 8330 from the positionrecorded on the MRI scan is determined as the offset of the prostate8330 in the optically sensed position of the probe 8700 relative to theposition at the time of the MRI scan. In some embodiments, the surgeonplans trajectories for insertion of the needle 7405 into the prostate8330 (from the medical image), and the robot 15 moves the guide tube 50to the desired 3D location for a needle 7405 to be inserted to thedesired depth (see FIG. 60). In some embodiments, an offset necessary toensure that the correct region of the prostate 8330 is targeted, isdetermined from the probe 8700 sensed offset, and the position of theguide tube 50.

In some other embodiments, the probe 8700 could be inserted down theesophagus to track movement of the stomach, intestines, or any portionof the digestive system. In some embodiments, it could be inserted intoa blood vessel to track the position of major vessels inside the body.In some embodiments, it could be inserted through the urethra into thebladder, ureters, or kidney. In all cases, it would help localizeinternal points for better targeting for therapy.

In some further embodiments, the probe 8700 could be combined with aconventional catheter for other uses. For example, fluid could beinjected or withdrawn through a hollow conventional catheter that isattached along its length to the probe 8700. Further, in someembodiments, a conventional balloon catheter could also be utilized. Theballoon could be temporarily inflated to secure a portion of the probe8700 within the urethra, or other position inside the body, ensuringthat the probe 8700 does not move forward or backward once positionedwhere desired.

A number of technologies for real-time 3D visualization of deformingsoft tissue and bony anatomy without the radiation are available and/orare in development. In some embodiments, the surgical robot 15 can usethese technologies during surgery, or other image-guided therapy. Insome embodiments, the use of real-time 3D visualization, automatednon-linear path planning and automated steering and advancement offlexible catheters or wires (for example wires 7405, 7410, 8600, or8110) in a non-linear path becomes increasingly important.

In some embodiments, it may be possible to visualize soft tissues inreal time by combining MRI (magnetic resonance imaging) and ultrasoundor contrast enhanced ultrasound (“CEUS”). For example, in someembodiments, an MRI scan and a baseline ultrasound scan would beobtained of the anatomy of interest. In some embodiments, landmarksvisualized on the ultrasound would be correlated to the MRI (forexample, borders of organs, blood vessels, bone, etc.). In someembodiments, a discrete set of key landmarks could be correlated suchthat the movement of other points of interest between these landmarkscould be interpolated. In some embodiments, a computerized geometricmodel (with its unmoved baseline position corresponding to the anatomyseen on the MRI) would be created. Then, when movements of the landmarkpoints are detected on ultrasound, the positions of the correspondingtissues visualized on the model can be adjusted. In some embodiments,the ultrasound would be allowed to run continuously, providing real-timedata on the positions of the landmarks. In some embodiments, changes inlandmark position would be used to update the model in real time,providing an accurate 3D representation of the soft tissues withoutexposure to radiation. In some embodiments, optical tracking markers 720attached to the conventional ultrasound probes could provide data on themovement of the probes relative to the anatomy, which would affect themodel calibration. In some embodiments, for accurate 3D positions of thepoints on the soft tissues, it may be necessary to utilize severalconventional ultrasound probes locked in a rigid orientation relative toeach other. In other embodiments, the ultrasound probes can besynchronized so that their relative positions are known or can beextracted. In some embodiments, optical markers 720 on multipleconventional ultrasound probes would allow registration of the multipleultrasound probe orientations in the same coordinate system. In somefurther embodiments of the invention, other methods for assessingdistance to tissues of interest, such as electrical conductivity,capacitance, or inductance of the tissues as mild electrical current isapplied.

In the modeling approach described above for visualizing soft tissues,it should be recognized that tracking a large number of landmarks helpsensure that the model is accurate. However, there is a trade-off thattracking a large number of landmarks may slow down the process, anddisallow real-time updating or require a lengthy registration process.In some embodiments, as fewer landmarks are tracked, tissue modeling topredict deformation of the non-tracked parts of the model becomesincreasingly important. In some embodiments, for tissue modeling, theelasticity and other mechanical qualities of the tissues are needed. Itmay be possible to assess the status of the tissues through a mechanismsuch as spectroscopy, where absorbance of light passed through tissuemight provide information on the composition of tissues, electricalconductivity, DEXA scan, MRI scan, CT scan or other means. Thisinformation could be provided to the computer model to allow betterestimation of soft tissue deformation.

Another possible mechanism for visualizing soft tissues can includeinjecting a conventional liquid tracer into the patient 18 that causesdifferent tissues to become temporarily detectable by an external scan.For example, the tracer could comprise a radioactive isotope that isattracted more to certain types of cells than others. Then, when thepatient is placed near an array of conventional radiation sensors, thesensors could detect the concentrations of the isotope in differentspatial locations.

Some embodiments include a mechanism to allow the user to control theadvancement and direction of a flexible catheter or wire (for examplewire 7405, 7410, 7600, or 8110) through an interface with the robot 15.In some embodiments, this mechanism can snap or lock into the robot'send-effectuator 30. In some embodiments, the guide tube 50 on therobot's end-effectuator 30 provides accurately controlled orientationand position of the catheter or wire at the point where it enters thepatient. In some embodiments, the mechanism would then allow the user tocontrol the rate and amount of advancement of the tube 50, the rate andamount of rotation of the tube 50, and activation of steering RF energy(for example, as described earlier with regard to steerable needle 7600in FIG. 40). In some embodiments, based on assumptions about thecondition of the soft tissues, and locations of obstacles such as bloodvessels, nerves, or organs between entry into the patient and thetarget, a non-linear path is planned by the software with parametersunder the user's control. For example, in some embodiments, the methodcan include a command sequence such as “advance 5 mm, activate steeringtoward an azimuth of +35°, continue advancing 5 mm while rotating at 1°per second,” etc. In some embodiments, during advancement of thecatheter or wire 7600 (or other wire 7405, 7410, or 8110), the real-timelocation of the tip is tracked using LPS or other visualization means.In some embodiments, the path plan is recalculated based on divergencefrom the expected path and advancement continues. In some embodiments,this advancing/turning snap-in mechanism can also be used with beveledneedles, taking advantage of the direction of the bevel, and the beveledface deflection force that moves the needle laterally away from the facewhen advanced. In some embodiments, software would plan which directionthe bevel should be oriented during different phases of needleadvancement.

In some embodiments, a mechanism similar to the one described above canalso be used for automatic hole preparation and insertion of screws. Forexample, in some embodiments, the end-effectuator 30 could have aconventional mechanism that would allow a tool to be retrieved from aconventional tool repository located somewhere outside the surgicalfield 17 In some embodiments, features on the tool holder would alloweasy automated engagement and disengagement of the tool. In someembodiments, after retrieving the tool, the end effectuator 30 wouldmove to the planned screw location and drill a pilot hole by rotatingthe assembly at an optimal drilling speed while advancing. In someembodiments, the system 1 would then guide the robot 15 to replace thedrill in the repository, and retrieve a driver with appropriately sizedscrew. In some embodiments, the screw would then be automaticallypositioned and inserted. In some embodiments, during insertion of thescrew, thrust and torque should be coordinated to provide good bite ofthe screw into bone. That is, the appropriate amount of forward thrustshould be applied during rotation so the screw will not strip the hole.

Some embodiments of the method also include algorithms for automaticallypositioning conventional screws. For example, in some embodiments,different considerations may dictate the decision of where the screwshould be placed. In some embodiments, it may be desirable to place thescrew into the bone such that the screw is surrounded by the thickest,strongest bone. In some embodiments, algorithms can be used to locatethe best quality bone from CT or DEXA scans, and to find an optimizedtrajectory such that the width of bone around the screw is thickest, orremains within cortical instead of cancellous bone for the greatestproportion. In some embodiments, it may be desirable to place the screwinto the bone at an entry point that is most perpendicular to the screw,or is at a “valley” instead of a peak or slope on the bonyarticulations. In some embodiments, by placing the screw in this way, itis less likely to skive or rotate during insertion and therefore likelyto end up in a more accurate inserted location. In some embodiments,algorithms can be used to assess the surface and find the best entrypoint to guide the screw to the target, while penetrating the boneperpendicular to the bone surface. In other embodiments, it may bedesirable to place screws in a multi-level case such that all the screwheads line up in a straight line or along a predictable curve. In someembodiments, by aligning screw heads in this way, the amount by whichthe surgeon must bend the interconnecting rod is minimized, reducing thetime of the procedure, and reducing weakening of the metal rod due torepeated bending. In some embodiments, algorithms can be used that keeptrack of anticipated head locations as they are planned, and suggestadjustments to trajectories that provide comparable bony purchase, butbetter rod alignment.

Some embodiments of the invention can use an LPS system that usestime-of-flight of RF signals from an emitter to an array of receivers tolocalize the position of the emitter. In some embodiments, it may bepossible to improve the accuracy of the LPS system by combining it withother modalities. For example, in some embodiments, it may be possibleuse a magnetic field, ultrasound scan, laser scan, CT, MRI or othermeans to assess the density and position of tissues and other media inthe region where the RF will travel. Since RF travels at different ratesthrough different media (air, tissue, metal, etc.), knowledge of thespatial orientation of the media through which the RF will travel willimprove the accuracy of the time-of-flight calculations.

In some embodiments, an enhancement to the robot 15 could includeinserting a conventional ultrasound probe into the guide tube 50. Insome embodiments, the ultrasound probe could be used as the guide tube50 penetrates through soft tissue to help visualize what is ahead. Asthe guide tube 50 advances, penetrating soft tissue and approachingbone, the ultrasound probe would be able to detect contours of the bonebeing approached. In some embodiments, this information could be used asa visual reference to verify that the actual anatomy being approached isthe same as the anatomy currently being shown on the 3D re-slicedmedical image over which the robot is navigating. For example, in someembodiments, if a small protrusion of bone is being approached deadcenter on the probe/guide tube 50 as it is pushed forward, the region inthe center of the ultrasound field representing the raised bone shouldshow a short distance to bone, while the regions toward the perimetershould show a longer distance to bone. In some embodiments, if theposition of the bony articulation on the re-sliced medical image doesnot appear to be lined up with the 2D ultrasound view of where the probeis approaching, this misalignment could be used to adjust theregistration of the robot 15 relative to the medical image. Similarly,in some embodiments, if the distance of the probe tip to bone does notmatch the distance perceived on the medical image, the registrationcould also be adjusted. In some embodiments, where the guide tube 50 isapproaching something other than bone, this method may also be usefulfor indicating when relative movement of internal soft tissues, organs,blood vessels, and nerves occurs.

Some embodiments can include a nerve sensing probe. For example, in someembodiments, for sensing whether a penetrating probe is near a nerve, anelectromyography (“EMG”) response to applied current could be used,enabling the ability of the robot 15 to steer around nerves. Forexample, as shown in FIG. 61, a probe 9400 could be used, with 1 or morecannulation offset from the probe's 9400 central axis that would enablea thin wire 9410 to extend from the tip 9405, ahead and to one side ofthe tip 9405. A beveled tip 9405 (or a conical or rounded tip) could beused.

In some embodiments, the probe 9400 could be advanced manually orautomatically and stopped, then the stimulating wire 9410 could beextended and current applied. In some embodiments, the EMG could bechecked to verify whether a nerve is in proximity. In some embodiments,the simulating wire 9410 could be retracted, and probe 9400 rotated sothat the portal for the stimulating wire 9410 is positioned at adifferent azimuth index. In some embodiments, the probe 9400 could againbe extended to check for the presence of nerves in a different regionahead. In some embodiments, if a nerve is encountered, it would be knownwhich direction the nerve is located, and which direction the probe 9400would need to be steered to avoid it. In some embodiments, instead of asingle wire 9410 extending and checking for a nerve, multiple wires 9410could simultaneously be extended from several portals around the probe9400. In some embodiments, the wires 9410 could be activated insequence, checking for EMG signals and identifying which wire 9410caused a response to identify the direction to avoid or steer. In someembodiments, it could be necessary to fully retract the stimulatingwires 9410 before attempting to further advance the probe 9400 to avoidblocking progress of the probe 9400. In some embodiments, thestimulating wires 9410 would have a small enough diameter so as to beable to penetrate a nerve without causing nerve damage.

As noted elsewhere in this application, the robot 15 executedtrajectories for paths into a patient 18 are planned using software (forexample, at least one module of the software running on the computingdevice including computer 100) where the desired vectors are definedrelative to radio opaque markers 730 on the image and therefore relativeto active markers 720 on the targeting fixture 690. In some embodiments,these trajectories can be planned at any time after the image isacquired, before or after registration is performed. In someembodiments, it is possible that this trajectory planning can be done onanother computerized device. For example, in some embodiments, aconventional portable device (such as a tablet computer, or a laptopcomputer, or a smartphone computer) could be used. In some embodiments,the 3D image volume would be transferred to the portable device, and theuser would then plan and save the desired trajectories. In someembodiments, when robotic control is needed, this same image volumecould be loaded on the console that controls the robot 15 and thetrajectory plan could be transferred from the portable device. In someembodiments, using this algorithm, it would therefore be possible for aseries of patients 18 to each to have a targeting fixture 690 appliedand an imaging scan, such as a CT scan. In some embodiments, the 3Dvolume for each patient 18 could be exported to different portabledevices, and the same or different surgeons could plan trajectories foreach patient 18. In some embodiments, the same or different robot 15could then move from room to room. In some embodiments, in each room,the robot 15 would be sterilized (or have sterile draping applied, andwould receive the scan and trajectory plan. The robot 15 would thenexecute the plan, and then move to the next room to repeat the process.Similarly, the portion of the registration process in which the 3D imagevolume is searched for radio-opaque markers 730 could be performed onthe portable device. Then, in some embodiments, when the robot 15arrives, the registration information and the trajectories are bothtransferred to the robot 15 console. In some embodiments, by followingthis procedure, the time of computation of the image search algorithm onthe robot 15 console is eliminated, increasing efficiency of the overallprocess when the robot 15 is required in multiple rooms.

Although several embodiments of the invention have been disclosed in theforegoing specification, it is understood that many modifications andother embodiments of the invention will come to mind to which theinvention pertains, having the benefit of the teaching presented in theforegoing description and associated drawings. It is thus understoodthat the invention is not limited to the specific embodiments disclosedhereinabove, and that many modifications and other embodiments areintended to be included within the scope of the appended claims.Moreover, although specific terms are employed herein, as well as in theclaims which follow, they are used only in a generic and descriptivesense, and not for the purposes of limiting the described invention, northe claims which follow.

It will be appreciated by those skilled in the art that while theinvention has been described above in connection with particularembodiments and examples, the invention is not necessarily so limited,and that numerous other embodiments, examples, uses, modifications anddepartures from the embodiments, examples and uses are intended to beencompassed by the claims attached hereto. The entire disclosure of eachpatent and publication cited herein is incorporated by reference, as ifeach such patent or publication were individually incorporated byreference herein. Various features and advantages of the invention areset forth in the following claims.

What is claimed is:
 1. A method for performing a medical procedure usinga medical robot system, comprising: providing a medical robot systemincluding: a robot including a display and an arm; an end effectorcoupled to the arm; a dynamic reference base capable of being coupled toa patient; an optical tracking system configured to track the positionof the arm, the end effector and the reference base, wherein the opticaltracking system includes optical markers positioned on the referencebase and the end effector; and a processor coupled to the robot and theoptical tracking system, providing, via the processor, imageregistration data of the patient and the robot system to the display;and implementing, via the processor, a planned trajectory causing therobot arm to position the end effector along the planned trajectory, andwherein the planned trajectory is non-linear.
 2. The method of claim 1,wherein the end effector is a tube having a pitch axis, a roll axis anda tube axis defining an axis of rotation of the tube.
 3. The method ofclaim 1, wherein the end effector element comprises a needle.
 4. Themethod of claim 1, wherein the end effector is coupled with a curvedguide tube.
 5. The method of claim 1, wherein the laser light ispositioned at a top portion of the end effector.
 6. The method of claim1, wherein when the end effector coincides with the planned trajectory,an auditory feedback is provided to indicate the desired trajectory hasbeen achieved.
 7. The method of claim 1, wherein the processorautonomously causes the robot arm to be adjusted to position the endeffector at the planned trajectory based on detected optical markers. 8.The method of claim 1, wherein the processor comprises aspecially-configured computer.
 9. The method of claim 1, wherein the endeffector position can only be moved along the planned trajectory. 10.The method of claim 1, wherein the end effector position can be lockedat a fixed distance from the patient
 11. A method for performing amedical procedure using a medical robot system, comprising: providing amedical robot system including: a robot including a display and an arm;an end effector coupled to the arm; a dynamic reference base capable ofbeing coupled to a patient; an optical tracking system configured totrack the position of the arm, the end effector and the reference base,wherein the optical tracking system includes optical markers positionedon the reference base and the end effector; and a processor coupled tothe robot and the optical tracking system, providing image registrationdata of the patient and the robot system to the display, implementing aplanned trajectory causing the robot arm to position the end effectoralong the planned trajectory, and wherein the planned trajectory iscurved.
 12. The method of claim 11, wherein the end effector is a tubehaving a pitch axis, a roll axis and a tube axis defining an axis ofrotation of the tube.
 13. The method of claim 11, wherein the endeffector element comprises a needle.
 14. The method of claim 11, whereinthe end effector is configured to match the curvature of the plannedtrajectory.
 15. The method of claim 11, wherein the processor modifiesthe planned trajectory based on the intra-operative imaging.
 16. Themethod of claim 11, wherein when the end effector coincides with thetrajectory vector an auditory feedback is provided to indicate thedesired trajectory has been achieved.
 17. The method of claim 11,wherein the processor autonomously causes the robot arm to be adjustedto position the end effector at the planned trajectory based on detectedoptical markers.
 18. The method of claim 11, wherein the end effectorposition can only be moved along the planned trajectory autonomously bythe robotic arm.
 19. The method of claim 11, wherein the end effectorposition can be locked at a fixed distance from the patient.
 20. Amethod of performing a medical procedure using a medical robot system,comprising: providing a medical robot system including: a robotincluding a display and an arm; an end effector coupled to the arm; adynamic reference base capable of being coupled to a patient; an opticaltracking system configured to track the position of the arm, the endeffector and the reference base, wherein the optical tracking systemincludes optical markers positioned on the arm, the reference base andthe end effector; and a processor coupled to the robot and the opticaltracking system, providing image registration data of the patient andthe robot system to the display, implementing a planned trajectorycausing the robot arm to position the end effector along the plannedtrajectory, registering the planned trajectory with data associated withthe optical markers and radiographic imaging, wherein the plannedtrajectory is non-linear and is modified based intra-operative imaging.